WO2016204627A1

WO2016204627A1 - Light weight oxygen free lamp assembly and method for fabrication of same

Info

Publication number: WO2016204627A1
Application number: PCT/NO2016/050131
Authority: WO
Inventors: Willy Kronborg; Roger Kronborg
Original assignee: Willy Kronborg; Roger Kronborg
Priority date: 2015-06-19
Filing date: 2016-06-20
Publication date: 2016-12-22
Also published as: NO20150809A1

Abstract

This publication relates to a LED illumination assembly (10) emitting light and/or LED lamp driver for use in dry, wet and potentially explosive environment filled with potting material and a method for providing a LED light lamp (10) configured to be explosion safe, comprising a housing containing one or more electrical heat generating devices and a heat transferring and cooling device (11) for transporting heat away from device(s) (10). The voids inside the housing is completely filled with a filling substance of an expanding type, filling at least a substantial part of the entire volume of the void(s) inside the housing in order to prevent penetration of water, to displace oxygen with the potting material, to control the thermal properties of the product and preventing penetration of gas into the interior of the LED lamp device or the LED driver (10).

Description

LIGHT WEIGHT OXYGEN FREE LAMP ASSEMBLY AND METHOD FOR FABRICATION OF SAME

Technical Field of the Invention

The present invention relates to a light weight oxygen free lamp assembly and/or a LED lamp driver, i.e. an electronic energy regulator for controlling the voltage or current supplied to the LED light bulb, assembled with LED technology suitable for use in dry, wet and potentially explosive environments and atmosphere and comprising a housing containing one or more electrical heat generating devices, and a heat transferring and cooling device for transporting heat away from device(s).

The invention relates also to a method for manufacturing and assembling such type of lamp assemblies.

Background for the Invention

Electrical systems in general and illuminating systems in particular, used in environments where there is a risk for the presence of explosive gases, should be configured in such way that the possibilities for appearance of sparks or electrical flashover or creeping current are eliminated. In addition the interior of lamp and/or driver of the system must also be protected against intrusion of moist, water. At the same time there is due to health, environmental and safety aspect a requirement of excellently illuminated working and operation environments, such excellent illumination being crucial as it has a large impact on working environment and the day/night rhythm of the personnel. Illumination of this type and produces much heat, thus representing a hazard. Illumination by light emitting diodes (LED) has been proposed for such purposes, also for example on offshore platforms and in oil refineries.

EP 2 587 136 A1 relates to a light source that includes an enclosure forming an internal volume. The enclosure has sides, a top and a bottom and at least one light emitting diode (LED) is arranged within the internal volume of the enclosure. The light source also includes a potting compound surrounding said at least one LED and filling said internal volume. This LED light disclosed is suitable for use in explosive and hazardous atmosphere, containing lighting fixture that is resistant to exposing electrical lighting discharge. The potting compound is in the form of silicone, acrylic, epoxy or urethane based material that is optical clear such that sufficient light may be emitted through the potting compound and the top.

Alternatively an air/LED interface may be used, where the potting may be used over an exterior side of the top of the enclosure. It should be appreciated that the disclosed solution requires an optical clear potting material and that the depth of the enclosure is shallow, allowing only for correspondingly small LED lamps. If large lenses are applied, a deep enclosure will be required with corresponding dramatic increase in total weight due to the increased amount of potting material required.

EP 2 088 369 A1 discloses a fixture for a LED lamp provided with a metal core circuit board arranged in a tray-shaped metal housing with direct heat transmission. LED lamps are arranged in the direction of the light emission openings on a side of the metal core circuit board turned towards the metal housing. The metal core circuit board and the LED lamps are projected with an electronic from a side surface of the metal housing. Polyurethane-basis based potting compound is completely sealed in the metal housing in a moisture-proof manner.

CN 204026534 U discloses an explosion-proof LED flood lamp. The

explosion-proof LED flood lamp comprises a lamp body which is connected with an explosion-proof rectifier, and the explosion-proof rectifier is arranged below the lamp body and connected with a support used for supporting the entire lamp body. The lamp body comprises a lamp housing, a light source and a reflector, a lamp source cavity and a wiring cavity which arte independently arranged in the lamp housing, the light source being arranged in the lamp source cavity. The reflector is arranged on the light source and the lamp housing is integrally formed by aluminium alloy in a pressure casting mode. A rectangular lampshade is installed on the lamp housing and the lampshade is fixed to the lamp housing by means of screws and can seal the lamp housing.

When filling or potting the interior of the prior art lamps, in order to prevent intrusion of water and/or gas into the lamp or in electronic ballasters, a potting material is commonly used, such potting material being of an conventional type where the starting weight of 160 g results in a weight of 1 to 2 kg.

There is a need for lighting systems that is compact, robust, having as low weight as possible in spite of large depth of the housing; being explosion safe and safe against sparks, etc., so as to avoid igniting gaseous hydrocarbon atmospheres; and at the same time being capable of excellent illumination and transferring heat await from the lamp unit/ and/or driver in an effective and safe manner.

Moreover, there is a need for a lighting system that has a long lifetime and that is not vulnerable to vibrations, impact, salt water spray, extreme temperatures, voltage drops. At the same time the lighting system shall be able to provide high illumination levels on long distances and being endurable. Another need is a system that has as low power consumptions as possible. In general, it should be appreciated that explosion safe LED lights are heavy and the larger light assemblies, the larger weight, such large weights requiring extra reinforced strongpoints in the supporting structures.

It is also a demand for a method for fabricating and assembling a lamp that is simple ad efficient and where all air is displaced from the interior of the lamp.

Summary of the Invention

A principle applied according to the present invention is to configure each LED lamp assembly or unit in such way that air/oxygen is removed from the interior of the lamp and/or a driver unit, eliminating any possible voids inside the LED lamp and/or driver unit containing oxygen and that the interior of the LED lamp assembly and/or driver unit are completely filled with an expanding potting material, i.e. a material that is heat resistant, inflammable and that expands and fills all voids inside the lamp and/or driver unit, forcing out any air or oxygen from the interior of the lamp and/or driver unit, i.e. air/oxygen is completely substituted by the potting material as a consequence of the potting materials expanding properties.

Another object of the present invention is to provide a LED lamp that is not dependent on use of an optically clear potting compound.

Yet another object of the present invention is to provide a LED lamp configu- ration constructed and configured in such way that air/oxygen is prevented from entering into the interior of the LED lamp configuration upon completed assembling of the various parts forming the LED lamp configuration.

An object of the present invention is to provide a safe illuminating system solution where the risk for explosion caused by the present of the illuminating system in an atmosphere that may contain explosive gases is eliminated or at least substantially reduced.

An object of the present invention is to provide a LED lamp and/or driver limiting production of excessive heat.

Another object of the present invention is to provide a lamp providing excellent illumination without producing excessive heat.

Yet another object of the present invention is to provide an explosion proof LED lamp suited for use on for example offshore platforms; oil refineries, and the like.

Yet another object of the invention is to provide an illuminating system that is robust, compact in size, has low weight and at the same time is easy to handle, and still providing excellent illumination even at a distance. A further object of the present invention is to provide a light emitting system that is suitable to be used also in dry, wet and potentially explosive atmosphere, where the possibility of igniting dust or gases can result in injury to personnel and damage to equipment or machinery.

An object of the present invention is to provide a LED lamp assembly provided with devices and configurations preventing overhearing of the lamp assembly and hence, its surroundings.

Another object of the present invention is to provide a lamp assembly where excessive heat produced by the lamp assembly may be transported and cooled by the surroundings in an efficient manner.

Another object of the present invention is to provide a LED lamp device that meets the ATEX Directive and other standards or guidelines for explosion protection in industry.

Yet another object of the present invention is to provide a LED lamp device that may prevent internal explosion inside the lamp itself without causing propagation of explosions or fire in flammable environments.

Another object of the present invention is to provide a LED light device that has lesser weight than the conventional LED light assemblies, and in fact as low weight as possible for maximum emission of light.

A further object of the invention is to provide a solution with as low depth and height as possible without renouncing on the brightness and strength of illumination, the light being made large for maximum illumination.

Yet another object of the invention is to provide a solution that opens up for use of larger lenses attached to the LED, with increase lighting effect without necessitating a proportional increase of weight.

Yet another object of the present invention is to provide a method for manufacturing the LED lamp devices so that air/oxygen is removed and so that all voids are filled with an expandable material in such way that the lenses of the diodes are not affected by the filling process of expanding material.

Another object of the invention is to provide a LED light system and/or a LED driver that meet the EX-m standard - Encapsulated Explosion proof equipment, keeping the flammable gas away from any hot surfaces and ignition capable equipment.

Another object of the present invention is to provide a method for potting securing that intrusion of water and/or gas into the interior of the lamp assembly, both during production and when in competed state, using an expanding potting material inside the lamp and around the electronical ballaster or transformer, having an end weight of only 300 g.

The objects of the present invention will be achieved by a device and by a method as defined by the independent claims, while a number of non-exhaustive embodiments, variants or alternatives of the invention are defined by the dependent claims.

According to the present invention a LED illumination assembly emitting light and/or LED lamp driver for use in dry, wet and potentially explosive environment is provided. The LED lamp assembly comprises a housing containing one or more electrical heat generating devices and a heat transferring and cooling device for transporting heat away from device(s). The void(s) inside the housing is completely filled with a filling substance of an expanding type, filling at least a substantial part of the entire volume of the void(s) inside the housing in order to prevent penetration of water, to displace oxygen with the potting material, to control the thermal properties of the product and preventing penetration of gas into the interior of the LED lamp device or the LED driver.

The filling or potting material may for example be an expandable type, such as for example Rencast™ CW 2215 from Huntsman with foaming agent DY 5054.

The LED device may be provided with a sealing ring attached at least around a circumference of the LED device at its free end. Moreover, according to one embodiment, the sealing ring may optionally be configured to form a seal between the circumference of the LED device and a transparent front, securing that the potting material is prevented from coming into contact with a light emitted lens surface.

Moreover, the sealing ring may be placed around a plastic body housing the optical lens and/or may be positioned in such that that when pressed towards a transparent front, a pressure tight sealing is provided.

The invention relates also to a method for fabricating a LED light lamp assembly configured to be explosion safe, where subsequent to completed assembly of a LED lamp assembly, the void or voids inside the LED lamp assembly is completely filled with an expandable potting material, forcing air/oxygen out of the interior of the LED lamp assembly. According to one embodiment the volume of unexpanded expandable potting material (31 ) filled into the interior of the lamp assembly may be around 25 % of the total void to be filled.

According to one embodiment the LED lamp assembly is provided with an overflow device for receiving excess potting material formed during the expansion and curing of the potting material to a foamed material. During the filling process, the LED lamp assembly may preferably be placed in an more or less upwards position during filling of the potting material, whereupon the LED lamp assembly is placed in a more or less horizontal curing position, and that the LED lamp assembly during the curing stage preferably are placed in an appropriate curing chamber for speeding up the curing process and reducing the curing time.

According to an embodiment of the invention, each LED device incorporated in the LED lamp assembly may during assembling provided with a sealing ring be placed around the circumference of the optical lens in such way that when

assembled the sealing ring is pressed sealingly against a transparent front, preventing the potting material to come in contact with the light emitting surface of the LED device.

According to the present invention a LED lamp assembly is provided, the lamp assembly having reduced weight compared with the prior art lamps, the lamp being safe in that the possibility of causing explosion in environments containing

hydrocarbon gases being eliminated because the lamp is not prone to sparks, creeping current or flashover.

It should be appreciated that the lamp is configured for use in commercial industries and is completely watertight, and prevents failure caused by water, dust or dampness.

According to the present invention an expandable, electronic potting material or ballaster is use, the change using such type of potting material is that the potting material during the expansion phase inside the lamp may produce an excessive pressure on the glass plate cover and other elements inside the lam, breaking the glass or causing undesired damage to said elements. Such challenge and risk is eliminated or at least substantially reduced by the method according to the present invention.

Short Description of the Drawings

The above and further features of the invention are set forth with particularity in the appended claims and together with advantages thereof will become clearer from consideration of the following detailed description of an exemplary embodiment of the invention given with reference to the accompanying drawings.

The invention will in the following be described further in connection with exemplary embodiments which are schematically shown in the drawings, wherein:

Figure 1 shows schematically and in exploded perspective an embodiment configured according to the present invention; Figure 2 shows schematically a cross sectional view of the LED-light embodiment shown in Figure 1 ;

Figure 3 shows schematically the first step in the process of forcing out air/oxygen by means of an expanding potting material;

Figure 4 shows schematically a possible second stage in process of filling an expandable foam or filler in the LED lamp assembly shown in Figure 3; and

Figure 5 shows schematically in perspective a part in the LED lamp assembly in enlarged scale, also showing the three major elements of the light source in expanded view, showing the features disclosed inside the circle marked A in Figure 4.

Detailed Description of Embodiments disclosed in the Drawings

Various aspects of the disclosure are described more fully hereinafter with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

The following description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. Although referring to a LED lamp assembly

embodiment it should be appreciated that the same principle may be applied in relation to a driver for a LED lamp assembly, or similar devices intended to operate in environments where sparks and overheating is to be avoided.

Reference throughout the specification to "one embodiment" or "an

embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases "in one embodiment" or "in an embodiment" in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures, or characteristics may be combined in any suitable manner in one or more

embodiments.

Figure 1 shows schematically and in exploded perspective an exemplary embodiment of a LED lamp configuration 10 according to the present invention. The LED lamp configuration 10 comprises a cooling device 1 1 , configured to form the backside of the LED lamp configuration 10. On the exposed surface of the cooling device cooling rib configuration 12 is arranged, increasing the heat transfer surface. On the opposite side, the cooling device 1 1 is provided with a supporting surface 13, provided with devices 14 for attachment of a printed circuit board (PCB) 15, provided with a number of LED devices 16 arranged in two rows. In association with the PCB 15, a cable input 17 and possibly a cable output 17' for connection with a LED lamp configuration 10 are arranged, for supply of electricity and possibly for enabling serial connection of LED lamp configurations 10. The LED lamp assembly 10 comprises also a transparent front 18 and a housing 19. The housing 19 is provided with aperture 20,20' for insertion of the cable input 17 and the cable output 17'. In order to assemble and hold the various elements of the LED lamp configuration together the unit is provided with bolting devices 21 , apertures 22 arranged in the cooling device 1 1 and threaded holes in corresponding bulb formed parts 23 on the inner surface of the housing 19.

Figure 2 shows schematically a cross sectional view through the embodiment of the LED-lamp configuration 10 disclosed in Figure 1 , seen through a pair of adjacent lenses 24 and lens houses 25. As shown the cooling device 1 1 comprises a number of ribs 12 extending out from a base plate 26 at an orthogonal angle. The ribs 12 shown are linear, but may have any other shape suitable for being cast in a casting tool. The base 26 may along each side be provided with side panels 27, preferably making an integral part with both the base 26 and the ribs 12, and being produced in the same material as for the base 26 and the ribs 12, forming a part of the cooling device 1 1 in order to provide as large surface area for cooling as possible. The material chosen for the cooling device 1 1 may for example be aluminium.

As indicated the base 26 is also provided with holes extending through the base 26 along the outer edges, suited for receiving bolts 21 forming a part of the bolting device. At the surface of the base 26 on the opposite side of the fins 12, the base 26 is provided with a surface 27 for attachment of the printed circuit card 15 with diodes 29 affixed thereto.

As indicated in Figure 2, the LED-devises 16 may comprise a lens house 25 incorporating a lens 24 and an associated protection 30 to protect the lens 24 from becoming damaged during the fabrication method, which will be described in more details below. The protection 30 may be fixed to the outer side surface of the lens house 25, extending at least around the upper part of the lens house 25 and also preferably covering the outer edge or rim of the lens 24.

The LED lamp configuration 10 comprises also a housing 19, configured to be fixed to the cooling device 1 1 , encapsulating all the lenses 24 and lens houses 25 and configured to extend upwards from the cooling device 1 1 . The housing 19 is sealingly fixed to the cooling device 1 1 . The upper surface of the housing 19 is provided with a transparent front 18, sealingly fixed to the housing 19 and having an exposed surface providing adequate illuminating surface to meet the required illumination requirements. The housing 19 may also be made of the same material as the cooling device 1 1 . In order to obtain airtightness the material chosen for the cooling device 1 1 , housing 19 and possibly the transparent front 18 and /or the configuration and design should be so as secure that the LED lamp configuration remain airtight even when heated up to design temperature.

According to the present invention the void formed inside the LED lamp device 10 between the base, the interior of the housing 19 and the LED-devices 16 is filled completely with a filling material 31. The casting resin may be a mineral filler containing epoxy resins or other types of resins for potting cavities in components containing electronic components or not, where a foaming agent is applied. The resin systems used should preferably be of a type that is able to cure in room temperatures, alternatively of a type requiring heating UV-light or other external factors for curing the compound. The foaming agent added to produce epoxy resin foam for light weight application. Preferably, but not necessarily a machine process is used for applying the mixed material.

Specifically, but necessarily, the filling material 31 may be of an expandable type filling the entire space and preferably forming closed cells, the foaming material preferably being of a type such as Rencast™ CW 2215 from Huntsman with foaming agent DY 5054; the curing agent may be HY 51 18 and Araldite CW 2215..

It should be appreciated that care should be taken during the process of filling the filling material 31 to avoid that the filing material 31 comes in contact with the lenses 24 and the illuminating surface of the lens houses 25, or at least the head of the lenses, since such detrimental contact may reduce the illumination effect of the LED lamp configuration 10.

Figure 3 shows schematically the first step in the process of forcing air/oxygen out of the assembled LED lamp assemblyl O, for example as disclosed in Figure 1 , by means of an expanding potting material 31. As shown, the assembled LED lamp assembly 10 may be placed in a suitable rig or fixture machine 32, arranged for example on a working table 33. A filling machine 34 may be arranged in association both with the jig 32 and the table 33, the filling machine 34 being configured to fill a expandable potting material into the interior of the LED lamp assembly 10 or the driver for the LED lamp assembly. The LED lamp assembly 10 or the driver may either be placed manually or automatically in the jig 32. A filling nozzle on the filling machine 34 is inserted into the aperture 20 configured to form an input port for the power supply cable, while the corresponding aperture 20' at the opposite end is sealed.

The potting material 31 is automatically mixed in the filling machine 34 prior to the filling and is applied through the aperture 20 at the end of the LED light lamp assembly 10. The potting material consist of standard potting material - one or two components, and a foaming agent, added to obtain the required expansion of the material during the curing process inside the voids of the LED lamp assembly 10 or driver assembly.

The potting machine may, dependent on potting material and the foaming agent fill the LED lamp assembly 10 or the LED driver up to approximately 25 % of the total available void or volume inside the assembly 10 or the driver assembly. Care should be taken so that the total volume of potting material and/or foaming is filled upon completed expansion or foaming of the potting material

As shown in Figure 3 the LED lamp module 10 is positioned in a more or less upright position during filling a, foaming and curing. It should be appreciated, however that the LED light module as an option may be placed in a more or less horizontal position during these stages, as disclosed in Figure 4. An expansion tube (Grey) may be fitted on the product to prevent excess material to be forced into contact with the outer body of the LED module or the less surface, due to overfilling.

During expansion, one end of the LED lamp is still open to atmosphere. The tube 35 is an open duct that has been pressed into the aperture, the purpose of which being limited to direct superfluous or excessive expanding material to be directed away from the exterior surface of the assembled LED lamp during the ongoing expansion of the potting material. Such over flow device also removes possible excessive pressure build up inside the interior of the LED light lamp or driver, removing a possible source for causing damage to the lenses and/or the LED.

Connection for electricity is achieved by means of a cable that previously has been soldered to the PCB. This cable may be directed out through an appropriate plug in the side panel (not shown) or through the cooling device

Figure 4 shows the LED lamp assembly in the phase where the voids are filled, at least partly, and where the potting material 31 is in the process of

expanding. As indicated, surplus or excessive material 36 due to possible overfilling 36, is escaping the interior of the LED lamp assembly through the expansion tube 35. Moreover, as indicated the LED lamp assembly is during this stage lying in a more or less horizontal position on the table 33.

Figure 5 shows schematically in perspective a part in the LED lamp assembly 10 in enlarged scale, also showing the three major elements of the light source in exploded view. As discussed above, in order to prevent the potting material 31 from getting into contact with the front and/or the side of the optical lens 24, a specially designed ring 30, for example made of rubber or other type of flexible and heat resistant material, is installed The ring 30 is placed around a plastic body 25, serving as a housing and protection for the optical lens 24. During and subsequent to the assembly, the ring 30 will be pressed against the transparent front 18 of the LED light assembly, preventing the expanding potting material from coming into contact with the lens 24 surface of the LED device 16, thus securing that the illuminating effect of each LED device is not reduced.

In case of the lightweight LED lamp device 10 is used in potentially explosive environments or atmosphere, but possibly also for other environments, the LED lamp device 10 may provided with Poly fuses, implemented on the printed circuit board 15 as second overheating security device. Moreover, separate non resettable fuses are implemented on the printed circuit board (15 as final security device may also be used in case of potentially explosive environments or atmosphere.

As mentioned above, the LED lamp assembly is classified as explosion proof equipment that can be used in potentially explosive dust or gaseous atmosphere or environments.

The weight of a LED lamp device according to the present invention may be limited to 6 to 20 kilos.

Claims

1 . A LED illumination assembly (10) emitting light and/or LED lamp driver for use in dry, wet and potentially explosive environment filled with potting material, com- prising a housing containing one or more electrical heat generating devices and a heat transferring and cooling device (1 1 ) for transporting heat away from device(s) (10),

characterized in that the voids inside the housing is completely filled with a filling substance of an expanding type, filling at least a substantial part of the entire volume of the void(s) inside the housing in order to prevent penetration of water, to displace oxygen with the potting material, to control the thermal properties of the product and preventing penetration of gas into the interior of the LED lamp device or the LED driver(10).

2. LED lamp device and/or LED driver (10) according to claim 1 , wherein the filling material is of an expandable type.

3. LED lamp device according to claim 1 or 2, where the LED device (16) is provided with a sealing ring attached at least around a circumference of the LED device (16) at its free end.

4. LED lamp device according to claim 3, wherein the sealing ring (30) is configured to form a seal between the circumference of the LED device (16) and a transparent front (18), securing that the potting material is prevented from coming into contact with a light emitted lens surface.

5. LED lamp (10) according to claim 3 or 4, wherein the sealing ring (30) is placed around a plastic body housing the optical lens.

6. LED lamp (10) according to one of the claims 3 to 5, wherein the sealing ring (30) is positioned in such that that when pressed towards a transparent front, a pressure tight sealing is provided.

7. Method for providing a LED light lamp (10) configured to be explosion safe, c h a r a c t e r i z e d i n that subsequent to completed assembly of a LED lamp assembly (10), the void inside the LED lamp assembly (10) is filled with an expandable potting material (31 ).

8. Method according to claim 7, wherein the volume of unexpanded expandable potting material (31 ) is around 25 % of the total void to be filled.

9. Method according to claim 7 or 8, wherein the LED lamp assembly is provided with an overflow device for receiving excess potting material formed during the expansion and curing of the potting material to a foam.

10. Method according to one of the claim 7 to 9, wherein the LED lamp assembly (10) is in an more or less upwards position during filling of the potting material, whereupon the LED lamp assembly is placed in a more or less horizontal curing position, and that the LED lamp assembly during the curing stage preferably are placed in an appropriate curing chamber for speeding up the curing process and reducing the curing time.

1 1 . Method according to one of the claims 7-10, wherein each LED device incorporated in the LED lamp assembly (10) is during assembling provided with a sealing ring placed around the circumference of the optical lens (24) in such way that when assembled the sealing ring is pressed sealingly against a transparent front (18), preventing the potting material (31 ) to com in contact with the light emitting surface of the LED device (16).