Elongated lighting device with adhesively affixed reflector and lighting element carrier, and method of assembly

A lighting device includes an elongate housing with a light exit window, a carrier assembly disposed within the housing and having a plurality of SSL elements, a reflector having a plurality of apertures and positioned between the housing and the carrier assembly, and an adhesive extending through the apertures and fixing the carrier assembly and the reflector to the housing. A method of assembling the lighting device and of a luminaire-including the lighting device are also disclosed.

CROSS-REFERENCE TO PRIOR APPLICATIONS

This application is the U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2015/065810, filed on Jul. 10, 2015, which claims the benefit of European Patent Application No. 14179439.6, filed on Aug. 1, 2014 and Chinese Patent Application No. PCT/CN2014/082796, filed on Jul. 23, 2014. These applications are hereby incorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to a lighting device, in particular to a lighting device comprising Solid State Lighting (SSL) elements.

The present invention also relates to a method of assembling the lighting device and to a luminaire comprising the lighting device.

BACKGROUND OF THE INVENTION

With a continuously growing population, it is becoming increasingly difficult to meet the world's energy needs and, simultaneously, to control carbon emissions to kerb greenhouse gas emissions which are considered responsible for global warming phenomena. These concerns have triggered a drive towards a more efficient use of electricity in an attempt to reduce energy consumption.

One such area of concern is lighting applications, either in domestic or commercial settings. There is a clear trend towards the replacement of traditional, relatively energy-inefficient, light bulbs such as incandescent or fluorescent light bulbs with more energy efficient replacements. Indeed, in many jurisdictions the production and retailing of incandescent light bulbs has been outlawed, thus forcing consumers to buy energy-efficient alternatives, e.g. when replacing incandescent light bulbs.

A particularly promising alternative is provided by solid state lighting (SSL) devices, which can produce a corresponding luminous output at a fraction of the energy cost of incandescent or fluorescent light bulbs. An example of such a SSL element is a light emitting diode (LED).

It is known to provide SSL lighting devices having a similar overall shape to fluorescent light tubes, i.e. tubular solid state lighting devices. Such devices can provide a form factor that is comparable with traditional lighting devices, this can aid market penetration as customers may like or be accustomed to the form factors of such fluorescent light tubes. These tubular SSL devices may be used to replace fluorescent light tubes or used in similar applications to fluorescent light tubes. In particular, these SSL lighting devices may be particularly easy to retro-fit in place of fluorescent light tubes.

An example of a prior art tubular SSL element-based lighting device comprises a tubular housing, within the tubular housing is a printed circuit board onto which a plurality of LED elements are mounted at regular intervals. In this known low-cost construction, the printed circuit board (PCB) is directly attached to the tubular housing using adhesive. However, this results in a very wide beam angle, which can be undesired. It is also known to provide a metal reflector for beam shaping between the PCB and the tubular body, however, the cost of this reflector may be high and the complexity of assembly of the lighting device is increased, which results in an overall more expensive device.

SUMMARY OF THE INVENTION

The invention seeks to provide a lighting device that can have a narrow beam and can be assembled in a straight-forward and, therefore, cost-effective manner.

The invention provides a lighting device comprising an elongate housing having a light exit window; a carrier assembly within the housing comprising a plurality of SSL elements; a reflector between the housing and the carrier assembly, having a plurality of apertures between the housing and the carrier assembly; and an adhesive affixing the reflector to the housing, the adhesive also extending through the apertures and further affixing the carrier assembly to the housing.

Such a lighting device can be assembled in a relatively economic manner. In particular, in assembling such a lighting device it is not necessary to separately apply adhesive to the carrier assembly and the reflector, accordingly, the number of steps involved in such assembly may be reduced. This advantage may also be obtained using an automated manufacturing process. As a result of these factors, the lighting device may be provided in a particularly economic way.

Further, the device may have a form factor that is comparable with traditional fluorescent light tubes, which may aid market penetration. For example, the lighting device may be a tubular lighting device having a tubular elongate housing.

The housing may be of glass. Use of a glass housing may be particularly economic. Further, glass housings may provide sufficient rigidity to enable the construction of lighting devices of some length without the need for additional structural elements beyond such a glass housing. Further, glass may be handled using techniques familiar to those working in the field of lighting devices.

The reflector may be dimensioned to reflect light emitted by said SSL elements under emission angles within a first range.

Accordingly, light may not directly exit the lighting device within said first range, instead the light is reflected. This can provide a lighting device having a relatively narrower beam. Lighting devices having a narrower beam may be advantageous in particular lighting applications. Further, as a greater proportion of the light emitted by the SSL elements may be provided in a desired area or location the effective luminous efficiency of the lighting device may be increased.

This may provide a beam angle of 260° or less. For example a beam angle of less than 260°, less than 240°, less than 220°, less than 200°, less than 180°, less than 160° or less than 140°.

Each of the plurality of apertures may have a regular shape, for example, rectangular, square or circular. This can help to provide a known, e.g. good, quality of attachment of the carrier assembly to the housing. Further, this can help to provide a known, e.g. relatively large, structural integrity to the reflector.

The plurality of apertures may form a regular array. This can also help to provide a known quality of attachment of the carrier assembly to the housing and/or to provide a known structural integrity to the reflector.

The reflector may be a foil or a paper. Such reflectors may be particularly economic.

The reflector may comprise a plastics material.

The reflector may comprise sheet metal.

The reflector may comprise a reflective coating. For example, the reflector may comprise a plastics material, which is not reflective, coated with a reflective coating.

At least a portion of the carrier assembly may be shaped to match the inner surface of the housing. This can enable the carrier assembly to have a particularly good attachment to the inner surface of the housing. Further, this can enable economic use of the adhesive.

At least a portion of the reflector may be shaped to match the inner surface of the housing. For example, the reflector may be shaped by the inner surface of the housing and a portion of the carrier assembly when the lighting device is assembled. This can enable particularly good attachment of the reflector and the carrier assembly to the housing. Further, this can also enable economic use of adhesive.

The carrier assembly may comprise a printed circuit board (PCB) and/or a heat sink. For example, the carrier assembly may be a PCB, or the carrier assembly may be a PCB mounted on a heat sink.

The invention also provides a method of assembling a lighting device comprising providing a carrier assembly comprising a plurality of SSL elements; providing a reflector having a plurality of apertures therein; applying adhesive to the carrier assembly and/or the reflector; and forcing the carrier assembly and a housing together to affix the carrier assembly and the reflector to the housing, wherein the reflector is between the carrier assembly and the housing; the apertures of the reflector are between the housing and the carrier assembly; and the adhesive is forced through the apertures to affix the carrier assembly to the housing.

As discussed above, in relation to the lighting device, such a method may be particularly simple and easy to carry out, consequently the method may provide lighting devices cost-effectively. In particular, the number of assembly steps can be reduced as it is not necessary to separately apply adhesive to the carrier assembly and the reflector. This advantage may also be obtained using an automated manufacturing process and, further, as the method is less complex the method may be easier to automate. Easier automation may allow for a decrease the cost of machinery required for automation and therefore a further decrease the cost of lighting devices provided by the method.

The reflector may be placed on the carrier assembly before the adhesive is applied. This can enable adhesive to be applied to the reflector and carrier assembly simultaneously, as the adhesive may be applied to the carrier assembly through the apertures of the reflector. This can enable further simplification of the method of assembling the lighting device and, consequently, may be particularly economic.

The invention also provides a luminaire comprising the lighting device as described above. Because, as described above, the lighting device may be provided in a particularly cost-effective way, the luminaire comprising the lighting device may also be provided in a particularly cost-effective way.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention are concerned with SSL element-based lighting devices. An area identified for improvement in the provision of SSL element based lighting devices is ease of construction. In particular, by providing SSL element-based lighting devices which are easier to fabricate it is desired to provide more cost-effective SSL devices.

Referring firstly toFIG. 1of the accompanying drawings, a partially assembled lighting device100can be seen to comprise an elongate housing110(shown in cross-section perpendicular to the elongate axis) having a light exit window112. There is a carrier assembly120within the housing110comprising a plurality of solid state lighting (SSL) elements122. There is also a reflector130between the housing110and the carrier assembly120. The reflector130has a plurality of apertures132(as shown inFIG. 3) between the housing110and the carrier assembly120. An adhesive140is provided for fixing the reflector130to the housing110; the adhesive140also extends through the apertures132for fixing the carrier assembly120to the housing110.

FIG. 2shows the partially assembled lighting device100ofFIG. 1in an assembled state. It can be seen that the carrier assembly120and the housing110have been forced together, to affix the reflector130to the housing110and to affix the carrier assembly120to the housing110by the adhesive140extending through the apertures132of the reflector130.

Accordingly, such a lighting device100can be assembled in a relatively cost-effective way. In particular, the carrier assembly120and reflector130can be affixed to the housing110in a simple way. In particular, it is not necessary to separately apply adhesive140to the carrier assembly120and the reflector130, potentially resulting in a reduction in the number of steps required for assembly of the lighting device100. Accordingly, the cost of assembling the lighting device100, and consequently the lighting device itself100, may be reduced. A reduction in the number of steps required for assembly may be particularly advantageous where the lighting device100is mass-produced, as any advantage may be obtained multiple times. Similarly, this advantage may be particularly prominent where the lighting device100is manufactured using an automated process, as in addition to reducing the number of steps required for assembly of the lighting device100the complexity of the machinery used to assemble the lighting device may also be reduced.

From the prior art it is known to affix a reflector between a housing and a carrier assembly, however this was done by affixing a carrier assembly to a reflector and separately affixing the carrier assembly and reflector to the housing. Such a process is more complex and as it involves separately applying adhesive to and affixing two pairs of components.

The adhesive140may be any suitable adhesive capable of affixing the carrier assembly120, reflector130and housing110to one another. For example, an epoxy, or a hot melt adhesive. Other examples will be apparent to the skilled person.

In the context of the present specification, the fact that the adhesive140extends through the apertures132does not necessarily imply that the apertures132are completely filled with adhesive, e.g. there may be voids where adhesive is not present within the apertures132. However, the adhesive may indeed completely fill the apertures132.

In selected embodiments, the solid state lighting (SSL) elements122may be Light Emitting Diodes (LEDs). Each of the SSL elements122may emit light of the same colour; alternatively, the SSL elements122may be configured to emit light of differing colours in order to provide a desired effect, as is known to the skilled person. For instance, such colours may mix inside the housing to yield a luminous output of a desired colour.

The housing100may have any suitable size and shape. For instance, the housing100may be sized and shaped so as to be used to replace fluorescent light tubes, which may aid market penetration. For example, the lighting device may be a tubular lighting device having a tubular housing.

The housing100may be of glass. Glass is a material which may be available relatively cheaply. In particular, glass tubular bodies may be obtained at a lower cost than plastic tubular bodies. In some cases glass tubular bodies may cost as little as one tenth of the price of comparable plastic tubular bodies.

Further, glass housings may provide sufficient rigidity to enable the construction of lighting devices of some length without the need for additional structural elements beyond such a glass housing. Further, glass may be handled using techniques familiar to those working in the field of lighting devices.

Another benefit is that glass may have better heat dissipation capability than many plastics materials. Therefore, a glass housing110may form at least a part of a heat sink used to regulate the temperature of the SSL elements122in use. Accordingly, use of a glass housing110may mean that it is not necessary to provide a separate heat sink. Alternatively, where a separate heat sink is provided, the heat sink may be smaller, as glass housings may better participate in heat dissipation than many plastics housings. Omission of a discrete heat sink can make assembly of the lighting device simpler and more economic, and use of a smaller heat sink may be more economic.

Additionally, use of plastic housings beyond a certain length may require the use of additional structural elements to prevent the plastic tubular bodies from bending or sagging. However, as glass materials are generally less flexible than plastics materials, additional structural elements to prevent sagging may not be required for lighting devices longer than the above mentioned certain length. Further, fixing the carrier assembly and reflector as described above does not necessarily require substantial structural elements. Accordingly, the combination of fixing the carrier assembly and reflector as described above and the use of a glass housing may be used to particular advantage, in that this structure and material combination is particularly simple and additional structural elements may not be required, even for lighting devices longer than the above mentioned certain length. Therefore, this combination may be particularly economic or cost-effective.

The reflector130may be dimensioned to reflect light emitted by the SSL elements122under emission angles within a first range. Therefore, light emitted from the SSL elements122within the first range may not directly exit the lighting device100. This can provide a lighting device having a narrower beam. Such lighting devices may be particularly advantageous in particular applications, for example, applications in which light is only required in particular areas or places, such as some office environments.

This may provide a beam angle of 260° or less. For example a beam angle of less than 260°, less than 240°, less than 220°, less than 200°, less than 180°, less than 160° or less than 140°. By way of non-limiting example, the beam angle may be in a range from 140° to 260°.

The beam angle may be defined as the angle that links the two points where the radiation is 50% of the maximum radiation in the centre.

The beam angle provided may be chosen according to the application in which the lighting device is used, as will be familiar to the skilled person.

The carrier assembly120may be or comprise any structure which is capable of supporting the plurality of SSL elements as may be known to the person skilled in the art. By way of non-limiting example, the carrier assembly120may comprise at least one of a printed circuit board (PCB) and a heat sink. For example, the carrier assembly120may be a PCB, or the carrier assembly120may be a PCB mounted on a heat sink. A PCB is a convenient way of supplying electricity to the solid state lighting elements122. The PCB may be of materials commonly used in the art and manufactured according to such procedures as are known to the skilled person. The heat sink may be of any suitable thermally conductive material as is known in the art, for example a metal such as aluminium.

The carrier assembly120may comprise additional components, for example, driver circuitry which may be included on a PCB. A heat sink may be used to prevent the components, such as SSL elements122, from overheating. A heat sink may be particularly advantageous where the SSL elements122are high luminous output SSL elements, as will be familiar to the skilled person.

The lighting device100may additionally comprise other elements known to those skilled in the art. For example, the lighting device100may comprise electrical connectors for connecting the lighting device100to an electrical supply. Additionally or alternatively, the lighting device100may comprise diffusers for diffusing light emitted from the SSL elements122in order to provide a more uniform appearance if this is desired.

The lighting device100may further comprise a driver. The driver may be mounted on the carrier assembly120. If a driver is not provided as part of the lighting device100, then a driver may be provided as part of a luminaire or in some other way external to the lighting device100.

The lighting device100may further comprise at least one cap. Such a cap may provide electrical connections between the SSL elements122and a power supply. For example, the cap may comprise connectors, such as pins, which connect to an electrical supply, e.g. an electrical supply of a fitting, such as a fitting of a luminaire.

FIG. 3shows a reflector130which may be included in any embodiment of the present invention. As shown inFIG. 3, each of the plurality of apertures132may have a regular shape, for example, rectangular, square or circular. The apertures132illustrated inFIG. 3are rectangular. Use of regular shaped apertures132can help to provide a known, e.g. good, quality of attachment between the carrier assembly120and the housing110. In particular the shape and size of the adhesive140which extends through the apertures and fixes the carrier assembly120to the housing110can be known. Further, use of regularly shaped apertures132can help to provide a known, e.g. relatively large, structural integrity to the reflector130.

Also as shown inFIG. 3, the plurality of apertures may form a regular array134. This can also help to provide a known quality of attachment between the carrier assembly120and the housing110. Further, a regular array134can help to provide a known structural integrity to the reflector130. InFIG. 3the regular array134is an array of rectangular apertures132, however, any regular shaped apertures may form a regular array134.

The reflector130may be a foil or a paper. Such reflectors130may be particularly economic. Alternatively, the reflector130may comprise a plastics material. As a further alternative, the reflector130may comprise sheet metal.

The reflector130may comprise a reflective coating. For example, the reflector130may comprise a plastics material, which is not reflective, coated with a reflective coating. Such reflectors130may be particularly economic as a relatively cheap plastics material may be used to construct the reflector.

Alternatively, the reflector130may be formed of any other suitable materials known to the person skilled in the art.

FIGS. 4 and 5illustrate an alternative embodiment of a lighting device100according to the invention. As the embodiment illustrated inFIGS. 4 and 5is substantially similar to that illustrated inFIGS. 1 and 2only the differences will be described and like reference numerals are used.

As shown in the embodiment illustrated inFIGS. 4 and 5, a portion124of the carrier assembly120is shaped to match the inner surface of the housing110. For example, the portion124may be an arcuate surface which mates with the housing110. This can enable the carrier assembly120to have a particularly good attachment to the inner surface of the housing110. Further, this can enable economic use of the adhesive140, in particular, as the carrier assembly120is shaped to match the inner surface of the housing110, less adhesive may be used to fill the void between the carrier assembly120and the housing110than if the carrier assembly110is not shaped so as to match the inner surface of the housing110.

Additionally, at least a portion of the reflector130may be shaped to match the inner surface of the housing110. For example, the reflector130may be shaped by the inner surface of the housing110and the portion124of the carrier assembly120when the lighting device is assembled, as shown inFIG. 4or the reflector130may be shaped only by the inner surface of the housing110during assembly, as shown inFIG. 2.

Additionally, the good attachment between the carrier assembly120, the reflector130and the housing110can provide good heat conductivity between the SSL elements122, the carrier assembly120, the reflector130and the housing110and hence good heat dissipation.

Embodiments of the invention also provide a method of assembling the lighting devices100described above. As shown inFIGS. 1 and 4, the method comprises providing a carrier assembly120comprising a plurality of SSL elements122and a reflector130having a plurality of apertures132therein. Adhesive140is applied to the carrier assembly120and/or the reflector130. Then, as shown inFIGS. 2 and 5, the carrier assembly120and the housing110are forced together to affix the carrier assembly120and the reflector130to the housing110. The reflector130is between the carrier assembly120and the housing110whilst the housing110and carrier assembly110are forced together. The apertures132of the reflector130are also between the housing110and the carrier assembly120and the adhesive140is forced through the apertures132to affix the carrier assembly120to the housing110.

As discussed above, in relation to the lighting device100, such a method may be particularly simple and easy to carry out; consequently the method may be cost-effective. In particular, it is not necessary to separately apply adhesive140to the carrier assembly120and the reflector130, accordingly, the number of steps involved in such assembly may be reduced.

The reflector130may be placed on the carrier assembly120before the adhesive140is applied. This can enable adhesive to be applied to the reflector and carrier assembly simultaneously, as the adhesive may be applied to the carrier assembly through the apertures of the reflector. This can enable further simplification of the method of assembling the lighting device and, consequently, may be particularly economic.

The assembly of the lighting device100may comprise using a jig. For example, the carrier assembly120may be placed on a jig with the SSL elements122facing downwards. The reflector130may then be placed on the carrier assembly120. The reflector130may be flat or, alternatively, pre-shaped to the form of the housing110or partially pre-shaped, for example with a curvature slightly less than the curvature of the housing. The adhesive140may then be applied to the carrier assembly120and reflector130. The housing110may then be placed around the carrier assembly120and reflector130. The jig may then be moved to force the carrier assembly120against the housing110. Consequently, the reflector130is squeezed between the carrier assembly120and the housing110. The adhesive140is forced through the apertures132to affix the carrier assembly120to the housing110. The adhesive140may then be cured.

As illustrated inFIG. 6, the lighting device100according to any embodiment of the invention may be advantageously included in a luminaire200such as a holder of the lighting device100, e.g. a ceiling light fitting, an armature for fitting underneath a cabinet or the like, an apparatus into which the lighting device is integrated, e.g. a cooker hood or the like, and so on.FIG. 6schematically depicts a luminaire200comprising a plurality of lighting devices100fitted in a housing210of the luminaire200. The luminaire200comprises a light exit window220. The light exit window220may comprise beam shapers such as one or more lens arrays, reflectors and so on. Alternatively, the light exit window220may simply be formed by an opening in the housing210. The internal surfaces of the housing210may be reflective to reflect light that exits the lighting devices100.

As illustrated inFIG. 6, the SSL elements122and the reflector of the lighting devices100may face the light exit window220of the luminaire200. Alternatively, the lighting devices100may be mounted in the luminaire200such that the SSL elements122and reflectors face away from the light exit window220. In such a case, the interior of the housing210of the luminaire200may be reflective. Consequently, the SSL elements122may not be directly visible to a user which may be desirable in certain applications, e.g. where glare is an issue.

The luminaire200including the lighting devices100may be capable of producing an appearance that is visually similar to the appearance produced by a luminaire comprising traditional fluorescent or phosphorescent light tubes. For example, the light exit window220of the luminaire200may be diffusive such that the SSL elements122and/or the lighting devices100are not individually perceptible to a user.

In a non-limiting example, the luminaires200may be ceiling armatures, e.g. armatures that are integrated in a suspended ceiling. Other examples of such luminaires200will be apparent to the skilled person.