Patent Publication Number: US-2005128752-A1

Title: Lighting module

Description:
This invention relates to a lighting module and related methods, and in particular, but not exclusively to lighting modules relying on LED light sources.  
      The use of LED&#39;s have a number of advantages over traditional filament bulbs: more rapid switching, more robust, increased life, lower power consumption, little heat transmitted in a forward direction. Therefore, although clearly advantageous a design parameters compared to filament light bulbs have changed.  
      With improvements in LED technology various new applications (for example traffic signals, car brake and indicator lights) are now being converted to LED based illumination with obvious maintenance and running cost savings.  
      This although described with reference to LED light sources may have wider applicability. With the advent of the blue LED in the 1990&#39;s it became possible to generate white light using a combination of red, green and blue LED&#39;s. Further, with the recent introduction of new, brighter blue and green LED&#39;s, when placed along existing high brightness red LED&#39;s (used predominantly in automotive high level brake lights) it is possible to mix the three basic primary colours.  
      The use of LED&#39;s may be widely applied to a variety of different fields as will be described herein. Examples of such LED technology can be found in patents such as WO 99/10867 and U.S. Pat. No. 6,211,626.  
      One area in which prior art filament lights have previously been used is stage lighting with an average stage using groups of lights for illumination. Such filament based lights projected a large amount of heat forwards and required colour filters to alter the colour of the light emitted therefrom. The colour filters were subject to heat deterioration and usually the deeper or more saturate a colour chosen, the greater the need to continually replace the filter. This was a common problem faced by long running performances.  
      Lighting systems, which use incandescent light bulbs to illuminate, may be connected to high current dimmer circuits. The dimmer circuits are normally located remote to the light fittings for ease of maintenance. Each light fitting may be wired to individual dimmer circuits, which require a suitable connection between the dimmer and the light fitting. With lighting systems sometimes using hundreds of dimmer circuits, there is substantial investment required to provide individual connection between each light fitting and dimmer. This has an impact on set-up of such systems, especially when portable lighting systems require extra time to install the electrical circuits using flexible cables.  
      Incandescent sealed beam light bulbs, when controlled via a current control (dimmer) device the lamp colour temperature varies as the current applied is reduced. This has the effect of changing from white light to yellow the dimmer the light intensity becomes.  
      Furthermore as the lighting industry improves working conditions, prior art filament based light may have a surface temperature of in excess of 200 degrees Celsius. This has an impact in which lights are chosen for aesthetic reasons, but also for risk assessment which can precludes prior art filament based lights from certain applications, without serious consideration placed on the heat dissipation problems.  
      The sealed beam bulb sometimes used in prior art filament based lights burns brighter than average bulbs, which radically affects the lifetime of a lamp. An average domestic bulb will be designed to last up to 2000 hours. The sealed beam prior art filament based light has an average lamp life of 400 hours. This can be greatly reduced if the lamp is repeatedly being flashed from zero intensity to full intensity. Once the lamp has been in operation the filament is exceptionally fragile and requires time to cool down before the unit can be moved. This problem obviously impacts on the cost of touring lighting systems, which may be in a different venue every night. Touring costs are further increased when lamp checking and replacement slows down the set-up procedures.  
      Lamps can also fail, when installed above the performance space, which require replacing before a show. Consequently, further risk is placed on the lighting personnel, who have a duty to ensure that all the lights work.  
      In some embodiments, the present invention takes advantage of light emitting diodes (LED&#39;s) which when disposed on a circuit board in a matrix arrangement, projects an alternative beam of light previously achieved with the sealed beam incandescent bulbs.  
      According to a first aspect of the invention there is provided a lighting module comprising a light source arranged to emit light and a cooling chamber being provided adjacent the light source with the cooling chamber being open to the atmosphere surrounding the lighting module, but substantially sealed from the light source.  
      An advantage of such an arrangement is that the light source is provided with cooling via the cooling chamber, but can be placed in outside environments without the light module being affected by moisture, etc.  
      The light source may be arranged to emit light generally in front of a plane through the source. The cooling chamber may be arranged on a side of the light source substantially opposite the side which is generally arranged to emit light.  
      The cooling chamber may have a heat sink arranged therein, preferably with one or more cooling fins arranged thereon. Such an arrangement is convenient because it provides an efficient structure for removing unwanted heat.  
      In a preferred embodiment the light source is mounted on a surface of the heat sink, preferably on a side opposite the one or more cooling fins that are provided.  
      The at least one cooling fin preferably extends into the cooling chamber. Such an arrangement is advantageous because the fin is exposed to the atmosphere that exists within the cooling chamber which is open to the atmosphere surrounding the lighting module. Therefore, an efficient method of removing heat from the light source is provided.  
      A fan (or other fluid moving means for example a pump, etc.) may be provided to assist the movement of fluid (generally gas, and in particular air) from outside of the lighting module into the cooling chamber. Such an arrangement is convenient because is assists in the cooling of the light source.  
      The cooling chamber may be divided into an inlet and an outlet region, possibly by a plate, or like member, arranged across the cooling chamber. The inlet region may be arranged to intake fluid from the atmosphere surrounding the lighting module. The outlet region may be arranged to have fluid expelled therefrom to the atmosphere surrounding the lighting module. Generally the inlet region is arranged adjacent the heat sink providing efficient cooling thereof.  
      Conveniently, the fluid moving means is arranged to move fluid from the inlet region to the outlet region.  
      In a preferred embodiment of the invention the inlet region and outlet region are arranged such that, in the usual operating position of the lighting module, the outlet region is generally above the inlet region. It will be appreciated that such an arrangement is convenient because it allows fluid heated by a heat sink in the inlet region to move by convection into the outlet region, thereby helping to improve the cooling efficiency of the light source.  
      A thermostat may be provided and arranged to control the fluid moving means. Such an arrangement is convenient because it allows the fluid moving means to operate only when required.  
      The lighting module may comprise an electronics containing chamber arranged to contain electronics used in powering and controlling the light source.  
      Preferably, the cooling chamber is between the light source and the electronics chamber. Such an arrangement is advantageous because it allows the light source to be cooled.  
      The cooling chamber may be sealed from the light source to an appropriate Ingress Protection rating. Further, the electronics chamber may be sealed from the cooling chamber to an appropriate Ingress Protection rating.  
      Preferably, the cooling chamber may be sealed from the light source to Ingress Protection rating IP54. Further, the electronics chamber may be sealed from the cooling chamber to Ingress Protection rating IP54.  
      The heat sink may be mounted on a wall fabricated from a heat conducting material of the lighting module such that heat can be conducted to the wall. The wall is preferably fabricated from a metal. In preferred embodiment the wall is fabricated from aluminium, but it will be appreciated that other metals such as steel, titanium, magnesium or the like may be suitable. The wall may be an external wall of the lighting module. Such an arrangement is convenient because it uses the wall to absorb heat from the light source and therefore helps to cool the light source.  
      Conveniently, the heat sink is sealed to the wall using a heat conductive sealing material. Such an arrangement is convenient because it helps to prevent the ingress of moisture from the cooling chamber.  
      The sealing material may be a heat conductive rubber. An appropriate seal is manufactured by Berquist UK Ltd of Unit 27 Darin Court, Crownhill Industrial Estate, Milton Keynes, MK80AD. Or an alternative supplier is Thermagon, Inc. 4707 Detroit Ave., Cleveland, Ohio.  
      The lighting module may comprise a circuit board having a thermally conductive layer. Conveniently, the thermally conductive layer is in thermal contact with a heat sink, which is preferably the wall of the housing.  
      The heat sink may comprise a housing of the lighting module.  
      According to a second aspect of the invention there is provided a lighting module comprising a light source arranged to emit light and a cooling chamber the light source being mounted adjacent an inlet region of the cooling chamber which is arranged to inlet cooling fluid and pass the cooling fluid to an outlet region wherein the inlet and outlet regions are arranged such that, in the usual operating position of the lighting module, the outlet region is generally above the inlet region.  
      It will be appreciated that such an arrangement is convenient because it allows fluid heated by the light source in the inlet region to move by convection into the outlet region, thereby helping to improve the cooling efficiency of the light source.  
      Generally, a fluid moving means, usually a fan, is provided and arranged to move cooling fluid from the inlet region into the outlet region. Such an arrangement assists the cooling provided by the convection cooling.  
      The light source may be mounted on a heat sink. The heat sink may have cooling fins that extend into the inlet region. It will be appreciated that cooling fins are advantageous because they maximise the area available for heat exchange.  
      In one of the preferred embodiments the cooling fins are arranged such that cooling fluid entering the inlet region passes over the cooling fins. Such an arrangement is convenient because it helps to maximise cooling.  
      A thermostat may be provided and arranged to control the fluid moving means. Such an arrangement is convenient because it allows the fluid moving means to operate only when required.  
      The lighting module may comprise an electronics containing chamber arranged to contain electronics used in powering and controlling the light source.  
      Preferably, the cooling chamber is between the light source and the electronics chamber. Such an arrangement is advantageous because it allows the light source to be cooled.  
      The cooling chamber may be sealed from the light source to an IP54 rating. Further, the electronics chamber may be sealed from the cooling chamber to an IP54 rating.  
      The electronics chamber may contain a power supply unit, which may be mounted upon a wall between the cooling chamber and the electronics chamber. An advantage of such an arrangement is that cooling fluid passing through the cooling chamber helps to keep the power supply unit cooled.  
      The heat sink may be mounted on a wall fabricated from a heat conducting material of the lighting module such that heat can be conducted to the wall. The wall is preferably fabricated from a metal. In preferred embodiment the wall is fabricated from aluminium, but it will be appreciated that other metals such as steel, titanium, magnesium or the like may be suitable. The wall may be an external wall of the lighting module. Such an arrangement is convenient because it uses the wall to absorb heat from the light source and therefore helps to cool the light source.  
      Conveniently, the heat sink is sealed to the wall using a heat conductive sealing material. Such an arrangement is convenient because it helps to prevent the ingress of moisture from the cooling chamber.  
      The sealing material may be a heat conductive rubber.  
      One or more holes may be provided in an external wall of the lighting module, which communicate with the cooling chamber. Preferably, there are a plurality of holes.  
      A portion of each hole may be arranged to communicate with the inlet region, and a portion of each hole may be arranged to communicate with the outlet region (i.e. any hole that is provided may span both the inlet and outlet regions). Such an arrangement is convenient because it provides a structure that is simple to manufacture.  
      A plate may be provided to substantially separate the inlet and outlet regions. The fluid moving means may be provided within the plate.  
      The lighting module may comprise a circuit board having a thermally conductive layer. Conveniently, the thermally conductive layer is in thermal contact with a heat sink, which is preferably the wall of the housing.  
      The heat sink may comprise a housing of the lighting module.  
      According to a third aspect of the invention there is provided a lighting module comprising a light source mounted upon a heat sink wherein the heat sink is mounted on a wall of the lighting module which is fabricated from a heat conducting material such that heat can be conducted to the wall.  
      Such an arrangement is convenient because it uses the wall of the lighting module as a heat sink which helps to remove heat from the light source.  
      The wall may be an external wall of the lighting module, and may be fabricated from a metal. Conveniently, the metal is aluminium, but it may also be fabricated from any one of the following metals: steel, magnesium, titanium.  
      Alternatively, or additionally, the wall may be fabricated from a heat conductive plastics material.  
      A fluid moving means may be provided in order to move cooling fluid through the lighting module. In particular the fluid moving means may be a fan, a pump, or the like.  
      The lighting module may comprise a spun aluminium body, which may be substantially cylindrical in cross section. The body may have a domed, closed, end, and may have an open end through which light is transmitted.  
      Use of a heat conducting wall in this manner may mean that sufficient cooling may be achieved without a fluid moving means. Clearly, the omission of a fluid moving means will in general reduce the power consumption of the lighting module, which in itself is advantageous.  
      Various features have been introduced, and their advantages discussed, in relation to each of the first, second and third aspect of the invention. The skilled person will appreciate that features discussed in relation to any one of these aspects of the invention are in general equally applicable to the other two aspects of the invention and have not been discussed in relation to each of the aspects in the sake of brevity.  
      The following features may be applicable in any of the first, second or third aspects of the invention detailed above.  
      The light source may comprise an LED light source, which preferably comprises one or more of each of a red, green and blue LED.  
      A controller may be provided and arranged to control the LED&#39;s. The controller may be arranged to control each LED of a particular colour together (e.g. all the red, all the green, all the blue), or may be arranged to address individual LED&#39;s, or any stage between these two extremes.  
      In such an embodiment the LED&#39;s may be arranged to be controlled to vary the intensity of the light emitted by any one colour of LED. Such an arrangement is advantageous because it allows the colour emitted by the lighting module to be varied and eliminates the need to use colour filters and can greatly enhance the choice of colour from the module.  
      The controller may be arranged to vary the intensity of a colour of LED by modulating the current supplied to the LED. The intensity of the LED may be adjusted by the use of constant current source known as Direct Linear Drive (DLD) known by people skilled in the art. The modulation scheme may provide a plurality of discrete colour intensities for each colour. For example roughly any of the following colour intensities may be provided: 64, 128, 256, 512, 1024, 2000, or any number in between any of these colour intensities.  
      The generation of the desired colour by the appropriate control of the LED&#39;s is advantageous because the light projected equates to a more efficient process than use of prior art filament bulbs and filters—prior art colour filter and bulb arrangements absorbed the white light, by subtracting out the other colours within the full colour spectrum. The use of three colours of LED uses additive colour mixing. This may result in a substantial saving to running costs compared with prior art bulb/filter arrangements. A further advantage of LED&#39;s controlled in this manner is that the colour remains constant as the current applied to the LED&#39;s is varied by way of the control.  
      A user interface may be provided allowing the controller to be manually programmed.  
      In alternative, or additional embodiments the controller may be programmed from device remote to the lighting module. For example, the controller may be programmed by downloading information into the controller, perhaps specific for the intended application.  
      Further, the controller may be programmed with pre programmed current control sequences thereby allowing the lighting module to generate fixed sequences of illumination.  
      The LED&#39;s may be of the polymer encapsulated through hole type or of the surface mount type.  
      The lighting module may comprise a circuit board having a thermally conductive layer. Conveniently, the thermally conductive layer is in thermal contact with a heat sink, which is preferably the wall of the housing.  
      The heat sink may comprise a housing of the lighting module.  
      The wall and/or housing of the heat sink may comprise an extrusion which provides a robust, yet cost effective means of providing the housing.  
      Conveniently, the heat conducting layer may comprise a metallic layer, which metal may be copper.  
      Components, such as the light source, may be mounted on the circuit board such that they pass through the heat conducting layer without contacting it.  
      According to a fourth aspect of the invention there is provided a method of cooling a light source comprising mounting the light source adjacent a cooling chamber which is open to the atmosphere surrounding the lighting module, but substantially sealed from the light source.  
      According to a fifth aspect of the invention there is provided a method of cooling a light source comprising providing a cooling chamber and mounting a light source adjacent thereto, and arranging the cooling chamber such that it comprises an inlet region adjacent the light source arranged to inlet cooling fluid and an outlet region arranged to expel cooling fluid and arranging the inlet and outlet region such that, in the usual operating position of the lighting module, the outlet region is generally above the inlet region.  
      According to a sixth aspect of the invention there is provided a method of cooling a light source comprising mounting the light source upon a heat sink and further mounting the heat sink on a wall of a lighting module containing the light source and fabricating the wall from a heat conducting material such that heat can be conducted to the wall.  
      According to a seventh aspect of the invention there is provided a lighting module comprising a light source mounted upon a circuit board wherein the circuit board comprises a heat conducting layer arranged to dissipate heat from the light source.  
      The heat conducting layer may be thermally connected to a heat sink.  
      The heat sink may comprise a housing of the heat sink.  
      The housing of the heat sink may comprise an extrusion which provides a robust, yet cost effective means of providing the housing.  
      Conveniently, the heat conducting layer may comprise a metallic layer, which metal may be copper.  
      Components, such as the light source, may be mounted on the circuit board such that they pass through the heat conducting layer without contacting it. 
    
    
      An embodiment of the invention is now described by way of example only and with reference to the accompanying figures of which:— 
       FIG. 1  shows a perspective view of a lighting module according to a first embodiment of the present invention;  
       FIG. 2  shows a side-on sectional view of a lighting module according to the first embodiment of the present invention;  
       FIG. 3  shows an end-on sectional view of a lighting module according to the first embodiment of the present invention;  
       FIG. 4  shows a side-on sectional view of a lighting module according to a second aspect of the invention;  
       FIG. 5  shows an end-on sectional view of a lighting module according to the second embodiment of the invention;  
       FIG. 6  shows a cross section through a further embodiment of the invention; and  
       FIG. 7  shows a perspective view of the embodiment shown in  FIG. 6 . 
    
    
       FIG. 1  shows first embodiment of a lighting module  100  suitable for use as a spotlight at, for example, an open-air music concert. The lighting module  100  comprises an approximately cylindrical casing  102  having a first, closed, end  101  and a second, open, end  103  opposite the first. The casing is a spun aluminium, often referred to as a par can, construction providing weight advantages over other folded steel constructions. The casing  102  includes a cooling chamber  215  along a portion of its length roughly midway between the first and second ends. The casing  102  comprises a domed portion in the vicinity of the closed end  102  which continues the roughly cylindrical casing  102 .  
      The cooling chamber  215  is defined by an area of the casing  102  with holes  106  equi-spaced about the circumference of the casing  102 . A portion of the dome forming the closed end  101  of the casing  102  is cut away and an insert  108 , providing a plate onto which connectors can be mounted, is placed therein. The insert  108  comprises a plastic support through which a network connector  110  and a power connector  112  pass in order that connections can be made to electronics contained within the casing  102 . The closed end  101  of the casing  102  further comprises a second cut-away portion over which a touch panel  114  is placed such that a user may, by touching the touch panel  114 , control electronics within the casing  102 . The touch panel  114  may be constructed of Mylar, or of some other material for use in a touch-sensitive control device.  
      The interior of the casing  102  is now described with reference to  FIG. 2 . As  FIG. 2  shows a cross-sectional view of the lighting module  100  shown in  FIG. 1 , like features are labelled with like numbers.  
      The lighting module  100  comprises a Light Emitting Diode (LED) array  202  providing a light source and arranged on a circuit board  204  mounted perpendicularly to a longitudinal axis of the lighting module  100  such that in use the light produced by the LED array  202  is directed towards the open end  103  of the casing  102 . The circuit board  204  upon which the array is mounted lies on a plane and the array projects light generally in front of the circuit board. The lighting module has a typical life of 100 000 hours. The circuit board  204  is situated at an edge region of the cooling chamber  215  towards the open end  103 . The LED array  202  comprises a plurality of polymer encapsulated LED&#39;s and in this example, six hundred and twenty LED&#39;s are provided.  
      Roughly two hundred LED&#39;s are provided of each red (i.e. produce red light when a current is applied), blue and green. The light from the LED array  202  passes through an acrylic dust cover  206  which is bonded to the circuit board  204  and also seals the LED array  202  such that moisture cannot contact the array  202  through the open end  103  of the casing  102 . The circuit board  204  is backed on to and in thermal contact with a heat exchanger  208 . The heat exchanger  208  is also shown in  FIG. 3  and comprises a planar surface  302  to which a rear face (i.e. opposite the LED array  202 ) of the circuit board  204  is attached. The side of the heat exchanger  208  opposite the planar surface comprises a plurality of raised fins  210  which are arranged to project into the cooling chamber  215 . The heat exchanger  208  is in thermal contact with the housing  102  via a moisture-proof but thermally conductive rubber seal  211 . The rubber seal  211  isolates the circuit board  204  and the LED array  202  from the cooling chamber  215  which is open to the atmosphere. The rubber seal  221  is a gasket seal and provides an Ingress Protection rating or IP54 between the cooling chamber  215  and an electronics chamber  220  described below.  
      The fins  210  project into the ventilating area, or cooling chamber, of the casing  102  such that air passing through the holes  106  will circulate about the fins  210  thereby facilitating heat exchange between the fins  210  and the air.  
      The cooling chamber  215  is divided into two areas by a circular baffle plate  212 , fabricated from aluminium and placed across substantially the entirety of the cross-section of the lighting module  100 . The baffle plate  212  is arranged such that it lies roughly midway across the holes  106  in the casing  102 , abuts the casing around substantially the entire circumference and so divides the ventilation area into two. The baffle plate  212  comprises a solid plate with a centre portion removed in which a fluid moving means, in this example a fan  214 , (shown in both  FIG. 2  and  FIG. 3 ) is placed.  
      The cooling chamber  215  is divided in two separated by the baffle plate  212  to produce an inlet region  217 , which contains the fins  210  of the heat exchanger  208 , and an outlet region  216 . The fan  214  is arranged such that air is drawn into the inlet region  217  of the cooling chamber  217 , through the holes  106 , passes through the fan  214 , into the outlet region  216  and is expelled through the holes  106 . Thus, the fins  210  are cooled by air being drawn across them, which in turn removes heat from the circuit board  204  and the LED array  202  mounted on the circuit board  204 .  
      Electronics to control the lighting module  100  are contained within an electronic chamber  220  which are separated from the cooling chamber  215  by a partition plate  218  and the dome shaped portion of the casing  102  towards the closed end  101  thereof. The partition plate  218  has about its circumference a moisture-tight seal  222  sealing it to the casing  102  to isolate the electronics chamber  220  from the cooling chamber  215 , which is open to the atmosphere through the holes  106 . Thus, the lighting module  100  may be thought of as comprising three areas: The water tight area in which the LED array  202  is mounted between the planar surface of the heat exchanger  208  and the dust cover  206 ; the cooling chamber  215  which is open to the atmosphere through the holes  106 ; and the electronics chamber  220  between the domed portion of the casing and the partition plate  218 . The two sealed areas are sealed to IP54 rating, as is the fan  214 .  
      The electronics chamber  220  contains a power supply unit  224 , a controller  226 , a thermostat  213  and a user interface unit  228 , all of which run at twenty four volts (as does the fan  214 ). Thus, when the lighting module  100  is running on full intensity for each of the red, green and blue LED&#39;s power consumption is seventy watts. The power supply unit  224  is connected to the power connector  112  and to the controller  226 . An external current source is then connected to the power connector  112 . The controller  226  is a computer processor and is arranged to receive instructions via the network connector  110  and/or from the user interface unit  228 . The user interface unit  228  receives inputs from the user via the touch panel  114 . The controller  226  is further arranged to receive inputs from the thermostat  213  to control the fan  214  and to control the LED array  202  via the circuit board  204 . Wires to the LED array  202  pass from the electronics chamber  220  to the array  202  through the partition plate  218 , the baffle plate  212  and the heat exchanger  208  and apertures through these plates/heat exchangers are sealed to ensure the array  202  and the electronics chamber  220  remain sealed.  
      The power supply unit  224  is mounted on the partition plate  218  so that cooling fluid circulating in the cooling chamber  215  cools the plate  218  and consequently helps to cool the power supply unit  224 .  
      It will be appreciated that the cooling chamber  215  is open to the atmosphere, and therefore to rain and moisture and therefore provides a “wet-zone”. Further, in outdoor use of the lighting module  100 , a plastic outer shroud will be used at least about the insert  108  to ensure that the electronics chamber  220  is kept dry. Equally, the rubber seal  211  is vital to protect the circuit board  204  and the LED array  202  from the “wet-zone” ventilation area.  
      In use of the lighting module  100 , colour and brilliance of the light produced by the lighting module  100  may be controlled by the controller  226  according to instructions received either via the network connector  110  or via user inputs made using the touch panel  114  and transmitted to the controller  226  by the user interface unit  228 . The controller  226  sends a signal to the circuit board  204  containing instructions as to which LED&#39;s should be lit. The skilled person will appreciate that LED&#39;s can be thought of as digital devices; they are either on or off. Therefore, to control the brightness of the LED the current to the LED is modulated in a manner to cause the LED to output the desired amount of light.  
      In this example, where the LED array  202  comprises six hundred and twenty LED&#39;s a third of which are blue, a third green and a third red, the colour of light produced by the lighting module  100  can be selected and altered. For example, the lighting module  100  may be required to provide white light, in which case the LED&#39;s of each colour group should be lit to equal brilliance. In this example, the controller  226  can cause the power supply unit  224  to provide current to produce a lighting module intensity of up to 4500 Lux, equivalent to a 500 watt sealed beam parabolic bulb. Each colour of LED can be controlled by altering the intensity of that colour LED (i.e. the intensity of the red, green and blue LED&#39;s can be altered independently from one another). Thus, any colour can be made by altering the intensity of the light emitted by one of the three colours of LED&#39;s. In this embodiment the controller  226  is capable of setting the brightness of each colour of LED to roughly 4096 distinct levels of brightness when run in 12 bit operation giving roughly 6.7 billion (4096×4096×4096) different colour outputs from the lighting module.  
      Historically the colour of light emitted from a lighting module has been controlled by introducing a plastic colour filter, it became possible to change the colour of the light by way of absorbing, or reflecting all other light than the specific colour chosen. Colour filter scrollers are also known which give a degree of alternative colour choice than one fixed colour. A disadvantage with these known solutions is that the colour of the filter can degrade when exposed to the heat emitted from traditional bulbs (especially of the sealed glass parabolic reflector type light source that helped to create a high light output device but also projected the heat forwards). Further, incandescent sealed beam light bulbs (as in the prior art), when controlled via a current control (dimmer) device the lamp colour temperature varies as the current applied is reduced. This has the effect of changing white light to yellow light the dimmer the light intensity becomes. Thus, the present arrangement removes the need for colour filters to change the light colour.  
      As further examples, the lighting modules  100  could be used to provide a “strobe” effect by switching the LED&#39;s on and off in unison several times a second; it will be appreciated that LED&#39;s have fast switching times when compared to bulbs. Alternatively, the red LED&#39;s could exclusively be lit such that the lighting module  100  produces red light. As a further example, the lighting module  100  could produce a green-and-blue flashing light by the controller  226  instructing that the green LED&#39;s then the blue LED&#39;s be lit in cyclic succession.  
      The controller  226  is capable of being programmed with a current control sequence such that the intensity and colour of the light produced by the lighting module  100  may be controlled according to a pre-set sequence. The current control sequence is input via the touch panel  114  and the user interface  228 , or via a network connection utilising the network connector  110 , establishing a binary data network.  
      The controller  226  also sends a signal to the fan  214 , which operates to provide an air-cooling system as described above when the thermostat  213  records a temperature of at least predetermined value. It will, however, be appreciated by those skilled in the art that the fan  214  may not be controlled according to temperature. It may, for example, operate at all times, or for set periods of time, when the lighting module  100  is in use.  
      It will be further appreciated that many uses of the lighting module  100 , such as for stage lighting, will require the lighting module  100  to be orientated such that the light is directed in a generally downwards direction. This has the effect that the heat exchanger  208  occupying the cooling chamber  215  will be often in use below the exhaust area  216 . Due to convection, this arrangement of the heat exchanger  208  is advantageous due to the extra cooling that will occur.  
      The heat exchanger  208  is in thermal contact with the aluminium casing  102  through the thermally conductive rubber seal  211  such that the surface of the casing  102  is effectively part of the heat exchanger  208 . This greatly increases the surface area available for cooling and again helps remove unwanted heat from the lighting module  100 . It will be appreciated that a problem with prior art lights is that the casing can become excessively hot and maximising the area for heat exchange helps to reduce the temperature of the casing  102 .  
      The lighting module  100  provides a source of coloured light without the need for filters. It can be used outdoors without modification and provides a practical alternative to traditional ‘spot light’ with a long life span and a low surface temperature.  
      If the lighting module  100  is to be used in external locations and is to be positioned to illuminate vertically upwards, a poly-carbonate cover should be placed over open end  103  to prevent liquids, for example rain water, from collecting within the lighting module  100 .  
      The controller  226  makes use of the DMX 512 protocol, which created a stream of data, produced by a lighting computer connected to a series of remote theatrical fittings, which could typically be lighting modules  100 .  
      The controller  226  is capable of generating DMX 512 protocol to control the device independent of connection to a computer network. The controller  226  transmits DMX 512 protocol (via the DMX out connection  110 ). The controller  226  is so designed to allow DMX 512 to be supplied via an external controller when connected to a network and addressed via the user interface  228  to run in “slave” mode.  
      The DMX 512 protocol was originally designed as a replacement to analogue based electronics requiring individual connection of each circuit (sometimes numbering hundreds of circuits), which delivered the signal from a remote lighting computer to the dimmer System. The DMX 512 protocol standardised differing protocols offered by different manufacturers.  
      DMX 512 protocol enables  512  individual control channels to be fed down one single data cable. Originally designed to improve communication between computer and dimmers.  
      With the advent of new robotic lights, all manufacturers adopted the DMX protocol as the industry standard.  
      The DMX protocol employs digital signal codes, when the lighting computer transmits a digital code a receiving device such as a dimmer, robotic light or other lighting devices, transforms the code into a function or command.  
      In hardware terms, the DMX protocol is delivered over metal data cables via the RS 485 hardware protocol, providing a bi-directional data link. The data cable consists usually of a twisted pair surrounded by an outer screen (earth) or shield. The first wire is known as data+ and the second as data.  
      DMX 512 protocol is normally transmitted at 250,000 bits per second over cable distances of hundreds of meters. Every byte transmitted has one start bit, normally used to ‘warn’ the remote device that the next start character is being sent. Eight data bits and two further stop bits are then sent. This roughly equates to the duration of each character is 44 microsecond.  
      The receiving device is addressed to a number between 1 and 512. The receiving device will then only respond to the data that is specific to that device within the binary data tree connected to the computer network.  
      The second embodiment of the invention has some features in common with the first aspect described above. In the Figures, these like features are labelled with like numbers.  
      The second lighting module  400  now described is shown in  FIG. 4  as comprising a funnel-shaped casing  402  having two opposing open ends: a wide end  401  and a narrow end  403 . The funnel-shaped casing  402  is spun aluminium, as before.  
      A fan  214  as described in reference to the first embodiment (shown in both  FIG. 4  and  FIG. 5 ) is placed in the narrow end  403 .  
      Inside the funnel-shaped casing  402  from the wide end  401  is partially inserted a frusto conical heat exchanger  408 . The heat exchanger  408  is also shown in elevation in  FIG. 5  and comprises a planar surface  502  having approximately the same dimensions as the wide end  401  of the funnel-shaped casing  402  to which a face of a circuit board  204  (described below) is attached (after insulation using a suitable medium). In this embodiment the heat conductive, electrically insulating compound described above is used. The side of the heat exchanger  408  opposite the planar surface  502  comprises a plurality of raised tapering fins  410  which are arranged to partially project into the funnel-shaped casing  402 . The tapering fins  410  are arranged to taper to provide a profile for the portion of the tapering fins  410  to be inserted into the funnel-shaped casing  402  which has a complementary shape to the inside of the narrowing funnel-shaped casing  402 . The heat exchanger  408  is in thermal contact with funnel-shaped casing  402 .  
      The second lighting module  400  further comprises a Light Emitting Diode (LED) array  202  arranged on the second face of the circuit board  204  mounted at a first face on the planar surface  502  of the conical heat exchanger  408  perpendicularly to a longitudinal axis of the second lighting module  400  such that in use the light produced by the LED array  202  is directed away from the funnel-shaped casing  402 . The LED array  202  comprises a plurality of polymer encapsulated LED&#39;s as before but in this embodiment, one hundred and sixty five LED&#39;s are provided.  
      Roughly fifty five LED&#39;s are provided of each red (i.e. produce red light when a current is applied), blue and green. The light from the LED array  202  passes through an acrylic dust cover  206  which is bonded to conical heat exchanger  408  as in the first embodiment.  
      The fan  214  is arranged such that air is drawn into the portion of the tapering fins  410  of the conical heat exchanger  408  that protrude from the funnel-shaped casing  402 . The air is then drawn through the portion of the tapering fins  410  of the heat exchanger  408  enclosed by the funnel-shaped casing  402 , the funnel-shaped casing  402  acting as a duct. The air then passes through the fan  214  and is expelled into the atmosphere. Thus, the tapering fins  410  are cooled by air being drawn across them, which in turn removes heat from the circuit board  204  and the LED array  202  mounted on the circuit board  204 .  
      Electronics to power the fan and the LED&#39;s of the second lighting module  400  are external to the module  400 . A connection (not shown) is provided in the narrow end of the funnel-shaped housing  402  to which an external current source may be connected.  
      The principal purpose of the second lighting module  400  is to provide white light, and therefore the all the LED&#39;s of the LED array  202  will be lit to a common level of brightness at one time. The overall brightness of the second lighting module  400  could however be controlled using the principals described above.  
      A further embodiment of the present invention is shown in  FIGS. 6 and 7 , which show a linear lighting module  601  which may provide a linear spotlight. Such linear lighting modules are suitable for use as an architectural light source or similar areas.  
      The lighting module  601  comprises an aluminium extrusion  602  which provides an outer body and also acts as a heat sink. As can be seen from  FIG. 6  the extrusion  601  can be approximated to a ‘U’ shape and the inner walls of the uprights of the ‘U’ each have a rebate  603  provided therein at roughly the mid point thereof. The rebates  603  provide a mechanical location into which a copper core circuit board  606  can be located.  
      A copper layer  604  provides a di-electric material as a central layer of the board  606 . Holes are provided within the copper layer  604  so that pins of components (for example LEDs  608 ) can pass through the copper layer without contacting it. The components are soldered in a usual manner to the underside of the board (e.g. at  610 ).  
      As will be seen from  FIG. 6  the copper layer  604  is expanded at edge regions  612 , 614  of the board  606  in order that the expanded portions can substantially fill the rebates  603  in order that good thermal contact can be made between the copper layer  604  and the extrusion  601 . A void  605  is provided underneath the circuit board  606 .  
      In use, as the LED&#39;s  608  and other components generate heat the copper layer  604  dissipates heat toward the aluminium extrusion, which also acts as a heat sink.  
      It will be appreciated that the use of the lighting module described above reduces the electrical energy required to produce the desired light. This is in itself advantageous, but has the further advantages that it has a long life (with a typical life of 100,000 hours), produces less heat (which in turn may reduce air conditioning requirements), requires no colour filters or periodic maintenance. Further, substantial savings may be achieved with power and distribution costs eliminating the need for remote dimmers, computer control and heavy gauge power distribution cables. It will be appreciated that LED&#39;s transmit virtually zero heat in the direction of light transmission.  
      It is envisaged that typical market applications for such lights include any of the following:  
      The retail environment, applications including window display illumination. 
          Including illumination of in store and external point of sale displays     Illumination of seasonal decorations.     In store accent lighting of architectural features such as ceilings, columns, walls, glazed lift shafts, water features, podium displays as well as illumination of shelving units.     Illumination of exhibition stands, product showrooms of all types including external and internal illumination of signs and information boards.        

      The built environment applications including the illumination both externally and internally of bridges, towers, buildings of architectural importance. 
          Places of worship, castles, railway stations,     Public buildings and commercial premises.     External and internal illumination of water features, flora and fauna displays such as the illumination of gardens.        

      The leisure environment applications including illumination of sports stadia, arenas, football grounds, recreation grounds. 
          Bars, public houses, private members clubs, night clubs, discotheques, health clubs gymnasiums, aerobic studios, bingo halls, casinos, racecourses.     Further applications include live performance venues such as theatres, concert venues, municipal halls, school halls and exhibition venues.     Other applications also include theme parks, fairground rides, amusement arcades, art galleries and museums, bowling alleys, water parks, and aquariums and cruise ships.     Further applications may also include the illumination of places of outstanding natural beauty such as caves, forests, cliff faces, monuments and pieces of public art and sculpture.        

      Photography, applications include the illumination of scenery, staging and performers within the film, television and still photographic markets. Either on location or studio based applications are possible.  
      Miscellaneous, The illumination of external locations, where coloured light or a changing coloured light may be used to help highlight a hazardous area. Applications include pedestrian crossings, zebra crossings and traffic junctions. As a suitable replacement for aircraft landing lights, using colour as a method of signalling.