The present invention relates to a light emitting assembly and in particular to the thermal controlling thereof. BACKGROUND OF THE INVENTION

Lamp technology may be seen in US2012/0300429, US2014/0016312, US2009/0295266, US2013/0170182, US2011/0103054, US2009/0190352, US2012/0218768,

US2014/0160737, US2012/0069571, US2015/0308628 and US9206972.

SUMMARY OF THE INVENTION In a first aspect, the invention relates to a light emitting assembly according to claim 1.

In this context, the assembly is formed of at least the housing and the plane element with the light emitters. These elements may be attached to each other, and additional elements, such as controllers or the like, may be added if desired.

The housing, or at least a portion thereof, preferably is translucent so that light emitted by the light emitters may exit the housing. The housing may be coloured or not coloured, may be clear or turbid, such as if comprising scattering particles. The housing may be made of polymer, plastic, glass, crystal or the like.

The housing may comprise additional elements, such as cooling elements. The outer contour or surface of the housing may be formed also of other elements, such as the below cooling elements.

The plane element is provided in the housing. The plane element may be provided completely within the housing, such as within an outer contour or surface thereof, or a portion of the plane element may extend outside of the housing or may form a part of an outer contour or surface of the assembly. The plane element preferably has one dimension which is smaller, such as at least 2 times smaller, such as at least 5 times smaller, such as at least 10 times smaller, than any dimension perpendicular to this dimension. The plane element may be formed by a single, plane element, such as a printed circuit board.

Naturally, the plane element may be formed of multiple elements attached to each other, such as an upper element with light emitters pointing upwardly and a lower element with light emitters pointing downwardly. The general plane and preferably thin shape is still preferred. When the plane element comprises multiple elements, these are dimensioned, such as provided with channels/holes, such that air is allowed to flow from one side of the assembly to the other.

The light emitters are attached to the plane element. In this context, a light emitter may be any type of light emitter, but light emitting diodes, LEDs, OLEDs, AMOLEDs, laser diodes or the like are preferred. The light emitters may be mounted to a surface thereon (such as by surface mounting) or may be manufactured as a part of the plane element, such as if the plane element is a wafer on/in which light emitters, such as LEDs are manufactured or provided. The light emitters are positioned so as to emit light in different directions, as they are provided at each of two major sides of the plane element so as to, when the plane element is horizontal, emit light upwardly and downwardly. Preferably, as will be described further below, light emitters may also be provided for emitting light in the plane of the plane element (horizontally in this situation). The light emitters may, for example, be positioned to as to be able to emit a homogeneous light intensity from the assembly. Thus, in one embodiment, the light from the assembly may have the same intensity, per area, around the assembly or a part thereof. However, light emitters may also be operated in smaller groups or individually so as to emit more light in one direction than in another - or emit light with different colours in different directions. In this context, an opening allows air flow from outside of the housing to inside of the housing. The opening may be dimensioned in number and/or size to allow a sufficient air flow to cool the light emitters and/or the plane element sufficiently. An opening is above the plane element when the opening is positioned on one side of a plane defined by the plane element. Another opening then is below the plane element when positioned on the other side of the plane. The plane may be defined by a surface of the plane element or a centre thereof, for example.

The channel or opening of the plane element allows air flow from one side thereof to the opposite side. Thus, air may flow through the plane element and thus cool it. Also, air may flow, on its way to/from an opening of the housing to the channel/opening of the plane element, along a surface of the plane element and thus also cool the plane element.

In order to cause air flow also along a surface of the plane element, the house openings may be provided, when the assembly is projected on to a plane parallel to the plane element, at different positions than that/those of the opening/s or channel(s) in the plane element.

The assembly comprises a cooling surface thermally connected to the light emitters and positioned in a vicinity of the first and/or second openings. The thermal connection to the light emitters may be a thermal connection via the plane element if this plane element is thermally conducting. A thermally conducting plane element may be a plane element comprising a metallic element, such as a PCB having a metallic (such as Al, Cu, Au, Ag, Fe or the like) base member on which individual electrical conductors are provided.

When the cooling surface is positioned in a vicinity of the opening, the air entering or exiting the opening will come into contact with the cooling surface and thus cool this surface which, due to the thermal contact with the light emitters, is hot. In this context "in the vicinity" means that the cooling surface is positioned at or in a path taken by air from the opening/channel of the plane element to/from the house opening.

The cooling surface may be positioned at or in the house opening or close thereto. In one embodiment, the cooling surface has a portion positioned at a distance from the house opening of no more than 10% of a distance (straight line, for example) from the house opening to the channel/opening of the plane element.

In one embodiment, the cooling surface forms part of a cooling element, such as a cooling element forming part of the housing. Thus, the cooling element may extend at least into the house opening and perhaps so far into it that a portion of the cooling element forms part of the outer surface or periphery of the assembly. Thus, also air flow around the housing and not entering the housing can take part in the cooling of the cooling element.

Preferably, the plane element is thermally conducting, so that it can be cooled by the cooling element by abutting the cooling element to the plane element. This abutment may be via an attachment or a biasing. Naturally, the plane element and cooling element could instead be a monolithic element. In one embodiment, the cooling surface is configured to guide air from the pertaining first/second opening and toward the channel/opening in the plane element. Thus, the cooling surface may have the additional function of actually guiding the air in the desired direction. This may be in order to facilitate the air flow, such as to reduce a friction or resistance to the air flow so that more air flows, per time unit, through the openings/channel.

In one embodiment, the cooling surface is a first cooling surface, the assembly further comprising a second cooling surface, the first cooling surface being positioned in the vicinity of the first opening and the second cooling surface being positioned in the vicinity of the second opening. Thus, the above considerations relating to the first cooling surface may also be relevant to the second cooling surface. Naturally, the same cooling element may form both the first and second cooling surfaces if desired. The cooling element may be made of any thermally conducting material, such as a metal, an alloy, a polymer, a combination thereof or the like.

In one embodiment, the plane element, when projected on to a predetermined plane, such as a plane parallel to the plane element, covers an area exceeding 80% of an area covered by the housing when projected on to the plane, such as the area covered by an inner surface of the housing, such as a portion of the housing provided in a plane of the plane element. On the one hand, a plane element of this size would, without the opening/channel, make difficult or directly prevent air flow from the first to the second house openings. On the other hand, a plane element covering this area will facilitate a larger number of light emitters (such as of different colours), dispersing these to have a lower heat concentration, having a larger surface for heat dissipation, and/or a more liberal positioning of the light emitters to e.g. obtain a desired emission characteristic, such as the possibility of obtaining a more homogeneous light emission from the assembly.

Naturally, the area may cover 85% or more, such as 90% or more, such as 95% or more. Actually, the plane element may extend to outside of the housing so as to take part of an outer periphery or surface of the assembly. In that case, the area may exceed that of the housing or the inner surface of the housing in the plane or close to the plane.

In one embodiment, one or more of the light emitters are configured to emit light in a plane of the plane element. This may be in order to obtain the above homogeneous light emission. In one situation, the one or more light emitters are provided at an extreme portion of the plane element, such as close to an outer edge thereof. This position may be at a distance from an edge of the plane element no more than 10% of a distance from that edge to a centre of the plane element.

Naturally, the one or more light emitters may be directed toward the desired direction of the light, but preferably, the one or more light emitters are directed to emit light perpendicularly to the plane element (such as when surface mounted on the plane element) and one or more reflectors are provided for directing light emitted by the one or more light emitters along the plane.

Preferably, all light emitters are surface mounted on to the two main surfaces of the plane element. A second aspect of the invention relates to a method according to claim 9.

Naturally, the above considerations, embodiments and the like are equally relevant in this aspect.

When the plane element and/or light emitters are hot, the general air flow may be from the lower opening to the upper opening via the opening/channel in the plane element, especially when no specific air flow generator, such as a fan, is provided. The assembly may be positioned in any desired orientation. Usually, the plane element is horizontal or at least substantially horizontal.

The method comprises cooling the plane element and/or light emitters by a cooling surface thermally connected to the light emitters and positioned in a vicinity of the first and/or second openings.

Then, the cooling surface could be a part of a cooling element abutting the plane element which then could be thermally conducting.

Also, the cooling surface could act to guide air from the pertaining first/second opening and toward the channel/opening in the plane element. In addition, the cooling surface could be a first cooling surface where also a second cooling surface is provided, the first cooling surface being positioned in the vicinity of the first opening and the second cooling surface being positioned in the vicinity of the second opening.

The air flow from the first housing opening to the second may be primarily through the channel/opening of the plane element. This may be due to the plane element, when projected on to a predetermined plane, as described above, covers an area exceeding 80% of an area covered by the housing when projected on to the plane. In one embodiment, light may also be emitted in a plane of the plane element. This may be obtained using one or more light emitters are provided at an extreme portion of the plane element. These light emitters may be positioned to emit light perpendicularly to the plane element (such as when surface mounted on the plane element) and one or more reflectors may direct light emitted by the one or more light emitters along the plane.

A third aspect of the invention relates to a light emitting assembly comprising a housing and a plane element provided in the housing and to which a plurality of light emitters are attached, wherein: the housing has a first opening below the plane element and a second opening above the plane element, the light emitters being provided at each of two major sides of the plane element and configured to emit light away from the pertaining side of the plane element, the plane element has therein a channel or opening allowing air flow through the plane element and - a shielding element preventing direct light transmission from one of the major sides of the plane element to the other of the major sides of the plane element through the channel or opening.

Naturally, all embodiments, situations and considerations of the first and second aspects are equally valid in relation to the third aspect of the invention. The aspects may be combined if desired.

When the light emitters are provided so as to emit light away from the plane element in both directions, there is a risk that light directed in one direction may be reflected, such as by the housing, and thus be directed through the channel/opening and thus be ultimately emitted in the other direction. However, when the light emission in the two directions is independently controllable, it may not be desired to have a portion of the light directed in one direction actually be directed in the other direction.

In this context, direct light transmission is light transmission without reflection or scattering. Light travels along a straight line if not reflected or scattered.

The shielding element acts to prevent such light from undesirably being emitted from the assembly in the other direction. A number of manners exist for preventing light from passing along the path which the air is allowed to flow.

Naturally, if the channel through the plane element was sufficiently bent or curved to itself prevent direct radiation there through, no shielding element is required. However, it is usually preferred that the channel through a plane element is a simple, straight hole or channel which, without the shielding element, would allow light penetration or transport.

Preferably, the shielding element is not light transmissive. The shielding element may be made of a metal, a plastic material, rubber, a polymer or the like. The shielding element may be attached to - or form part of - the plane element and thus take part in the cooling thereof. The shielding element typically will be positioned in the vicinity of the opening/channel and thus be positioned in or at the air flow through the channel or opening. Thus, if the shielding element is thermally conducting, it may be thermally connected to the plane element to take part in the cooling.

In one embodiment, the shielding element is U-shaped, such as in a plane perpendicular to a plane of the plane element, having two leg portions at least partly extending on either side of a portion of the plane element. The U-shape may be symmetrical around an axis which may extend in a plane of the plane element.

When at least a portion of one leg extends over a portion of the plane element, light directed perpendicularly to a plane of the plane element will not be able to enter the channel/opening, as the leg will block it. In other words, when projected on to a plane of the plane element, one or both legs cover all of the channel/opening.

Light could also impinge on the shielding element or the opening/channel from an angle. In that respect, it may be desired that the shielding element, such as combined with the plane element, forms a duct or channel, which is bent at least 90 degrees, such as at least 120 degrees so that a straight line, not touching the walls of the channel, does not exist through the channel. Again, in this manner, light cannot travel through the opening/channel without reflection/scattering.

In one situation, the shielding element is shaped so that, in all cross sections in planes perpendicular to a plane of the plane element, no straight line can exist from above the plane element to below the plane element, through the channel or opening and not intersecting the shielding element. Clearly, the shape of the channel/opening and the shielding element may be selected in a wide variety of manners. In one embodiment, the assembly further comprising a cooling surface thermally connected to the light emitters and positioned in a vicinity of the first and/or second openings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, preferred embodiments will be described with reference to the drawings, wherein:

Figure 1 illustrates a cross section of one embodiment of an assembly,

Figure 2 illustrates an enlarged portion of a rim portion of the embodiment of figure 1. Figure 3 illustrates an enlarged portion of a rim portion of the embodiment of figure 1, cross-section is taken at a different rotational position compared to figure 2.

- Figures 4 and 5 illustrate different embodiments of a shielding element.

DETAILED DISCLOSURE OF THE INVENTION

In figure 1, an assembly 10 is seen having a housing 12 generally formed by two half portions 121 and 122 which are translucent in order for light generated by light emitters 141 to exit the assembly 10 generally in an upward and downward direction. In the housing, a plane element 14 is provided on which the light emitters 141 are provided. The plane element 14 preferably is thermally conductive, such as if comprising a metal, such as Al.

A rim portion of figure 1 is blown up in figure 2, from which it is seen that the housing further has an outer rim portion 123, which is also translucent, so that light emitted by light emitters 142 may be reflected by reflectors 17 and exit the housing in a direction to the side.

In general, the assembly is configured to emit light upwardly, downwardly and to the side but independently of each other. Thus, the assembly may be used for generating a large number of lighting conditions or moods simply by varying the manner in which the light emitters 141/142 are operated (see also PCT/EP2017/051276 filed on even date and with the title "An assembly of a shade and a light source" and which is hereby incorporated by reference). Naturally, not only the light intensity but also the colour of the emitted light may be controlled as may any pattern in which the light is output. Usually, it may be desired that the light emitted upwardly, downwardly and/or to the side is as homogeneous as possible, but situations may exist where a more narrow beam is emitted in a direction or where light in e.g. the downward direction is brighter in one downward direction than in another (perhaps more bright to the right than to the left in the drawing). The skilled person will easily see that when each light emitter may be controlled independently of all other light emitters, a vast amount of modes may be obtained.

Naturally, heat is generated when the light emitters are operated. In order to control the cooling of the light emitters, two cooling elements 163 and 164 are provided which define openings 161 and 162 in the housing 12. Thus, air is allowed to enter and exit the housing through the openings.

In order to facilitate air flow in the housing, the plane element 14 has one or more openings 143 there through to allow air to flow from the lower opening 161 to the upper opening 162 and/or an opening 165 at the top of the housing. Naturally, any number of openings may be provided, but an opening below the plane element 14 usually will allow cooler air to enter the housing and an opening above the plane element 14 will allow hotter air to escape the housing. Actually, openings may be provided both below and above each of the extreme portions of the cooling elements 163/164. The opening(s) may be selected at positions where the air will flow over the surface of the plane element and/or the light emitters to cool these.

However, cooling elements are preferred, along a surface of which the air flows, which cooling elements are thermally connected to the plane element 14 so as to, consequently, remove heat from the plane element. Naturally, the cooling elements may be provided entirely inside the housing and in the vicinity of the openings so that the air flowing through the openings cool the cooling elements, but the cooling is better, and the appearance of the assembly is very exclusive, when the cooling elements extend to also the outer periphery of the assembly to form a part of the outer surface thereof. In figure 1, the cross-section is taken at a rotational position (the assembly housing is rotationally symmetric around an axis in the plane of the drawing and perpendicular to the plane of the plane element 14) where the cooling elements 163/164 seem to cover the openings 143. At other rotational positions, the cooling elements do not cover the openings so that air is allowed to flow from below the plane element to above the plane element (see figure 3). Naturally, any number of openings 143 may be provided and any position thereof may be selected, such as at a centre of the plane element 14, at a periphery thereof, between these positions or a combination thereof.

Preferably, the plane element 14 comprises the light emitters 142 for generating light to be emitted to the side (in the plane of the plane element) of the assembly 10. These emitters 142 preferably are provided rather close to the outer rim of the assembly 10 and thus housing 12. Therefore, the plane element preferably extends to rather close to the rim of the housing 12 and thus covers a majority of the area, when projected on to a plane parallel with the plane element 14, of the housing 12. Nevertheless, the openings 143 facilitate air flow inside the housing from below the plane element to above the plane element.

The light emitters 141 and 142 preferably are surface mounted on the plane element 14, which therefore preferably is a Printed Circuit Board. Then, the cooling elements may contact virtually any portion of the plane element and still assist in cooling the light emitters.

In an extreme case and/or in the situation where the plane element 14 is not or not sufficiently thermally conducting, a cooling element may be used which extends over larger portions of the plane element such as all portions of the upper and lower surface thereof and even close to and/or between the light emitters in order to remove heat from the light emitters. Naturally, a cooling element extending to the light emitters should still allow the light emitted to reach the housing 12. At the outer parts of the plane element 14, light emitters 142 are provided as well as reflectors 17 in order to output light in the horizontal direction and/or in the plane of the plane element 14. Naturally, the light emitters 142 could alternatively be angled to directly emit the light in the desired direction, or the cooling elements 163/164 could be provided with reflecting surfaces to also act as reflectors. Figure 3 illustrates an enlarged cross-section of the rim portion of an embodiment corresponding to that described in figure 1 taken at a different rotational position compared to figure 2. In this embodiment, the monolithic cooling element 163 is replaced by an assembly 263 formed by the elements 263a, 263b and 263c, which together are provided in the same position and perform the same function. Compared to figure 2, the opening 143 is now open. It is seen that the cooling element 164 is replaced similarly by the assembly 264.

The housing 12 is formed by the two half portions 121 and 122, and the diffuser 123, which are all translucent to allow light generated by the light emitters 241a, 241b, 242a and 242b to exit the assembly. The light emitters 241a emit light upwardly toward the portion 121 and the emitters 241b emit light downwardly toward the portion 122. The emitters 242a emit light upwardly toward the reflector defined by portion 263b (instead of the separate reflector 17 of figure 2) and the emitters 242b emit light downwardly toward the reflector defined by portion 264b. As described above, air flow is facilitated from opening 161 through the opening 143 to opening 162 (and/or opening 165). The elements 263/264b/c are positioned in this air flow and are connected to the PDB 14 and thus cool the light emitters.

Also, the elements 263/264a are connected to the PCB 14 and are provided in the air flow and thus assist in the cooling. However, the elements 264/263a together have another function, which may be additional to the cooling or alternative to the cooling altogether. When the light emitters 241a are controllable or operable independently of the light emitters 241b, a light mode may be one where light is desired output by the emitters 241a but not the emitters 241b. Thus, no light is desired downwardly in the drawing. Thus, it is not desired that light is reflected by e.g. the portion 121 through the opening 143 to be directed downwardly.

The optional or additional function of the elements 263/264a is that of preventing light from passing from above the PCB 14 to below the PCB 14 through the hole 143. To this effect, the shielding element formed by the portions 263/264a is shaped so that no light is able to pass from above the PCB 14 to below the PCB 14, through the hole 143 and without reflection or scattering. Preferably, the shielding element is not light transmissive.

A number of manners exist of obtaining this shielding. In general, direct light transfer from one side to the other of the PCB 14 requires that a straight line may be drawn, such as in a cross section of the assembly, which may be followed by light. If a straight line may be drawn, light with that direction would be able to travel from the one side to the other. Figure 3, the shielding element is U-shaped where the two legs (of 263a and 264a, respectively) extend over the PCB 14 - or the PCB 14 extends between the legs. Thus, in this cross section, light cannot pass from e.g. the element 121 to the element 122 through the opening 143 without reflection or the like at the elements 263/264a.

In figures 4 and 5, different manners of ensuring that light cannot directly and unhindered pass the opening 143 are illustrated. Such a design increases a total cooling surface and further improves thermal conductivity of the assembly. In particular, a cooling hole 270 formed by the portions 263a, 264a and the opening 143 in the plane element 14 provides increased cooling surface as air entering the housing 12 through a lower opening 261 is passing through the cooling hole 270 while interacting with the cooling elements 264a and 264b and finally exiting through the top opening 265. Furthermore, the cooling hole 270 is designed as a light trap so that light from bottom light emitters 241a does not go through the cooling hole 270 to the top area. Also, light from top light emitters 241b does not go through the cooling hole 270 to the bottom area. However, air flow is not trapped by the cooling hole 270. Figure 4 illustrates the element 263a overlapping the opening 143 when projected on to a plane of the PCB 14 in figure 3. Thus, light from directly above the opening 143 cannot pass to below the element 264a. If only light perpendicular to the plane of the PCB 14 is to be blocked, a single of the elements 263/264a is required.

However, if light is also seen from the side of the opening or at an angle, different from perpendicular, to the plane of the PCB 14, other embodiments may be desired. In one embodiment illustrated in figure 5 and which is a cross section of the opening at the hatched line of figure 3, multiple openings 143 exist and the elements 263/264a form, with the PCB 14, a channel for each opening 143. Clearly, in order for light to enter the channel, it must be at least substantially aligned with the channel. However, in that case, the light will experience the bent channel illustrated in figure 3, which channel bends more than 90 degrees and thus prevents direct passage of light from above the element 263a to below the element 264a.

It may be desired that the shielding element and the opening together form a passage which light has to pass to travel through the opening from e.g. the space between the element 221 and the PCB 14 and to the space between the element 122 and the PCB 14. This passage may be shaped so that no straight line exists from an opening thereof (into the space between the element 221 and the PCB 14) and to an opposite opening thereof (to the space between the element 122 and the PCB 14).

Naturally, a wide variety of materials and embodiments may be chosen from. The housing preferably is translucent and not coloured, so that the colour of emitted light may be controlled by the light emitters. However, a coloured, translucent housing or a part thereof may be selected.

Preferably, the light emitters are positioned so that a homogeneous light pattern may be obtained so that the same amount of light may be emitted in all directions or substantially all directions from the assembly. The light emitters may then be controlled to deviate from this homogeneous emission so that more light is emitted in one direction (up, down, to the side, toward different positions around the assembly). Thus, a spot light may be obtained where light is predominantly emitted toward e.g. an area below the assembly, where another mode may be the emission of light toward a larger are below the assembly.

The housing may be translucent and turbid, such as comprising light scattering particles so that a more focused beam from a light emitter may be de-focused or diffused to obtain a more, compared to the beams emitted by the individual light emitters, diffuse and homogeneous light emission from the assembly. The openings may be elongate openings allowing air to flow there through. The width or area of the openings may be selected so that a suitably large/small air flow is obtained to obtain the desired cooling.

Preferably the plane element is a single plane element on to which all light emitting elements are attached. Also, circuitry may be attached to the plane element to receive instructions (typically wireless, such as via Bluetooth, WiFi, Z-wave or the like) and to control the light emitters.

The plane element preferably is thermally conducting so that the cooling element may contact the plane element at one position and still be able to cool other parts of the plane element and thus the light emitters. One type of plane element is a PCB based on aluminium, so that electrical signals may be fed on surface conductors thereof while the base of the PCB is thermally conducting and able to transfer heat.