Abstract
A light emitting diode, LED, filament arrangement (100), comprising at least one LED filament (120) comprising an array of a plurality of light emitting diodes (125), LEDs, wherein the at least one LED filament comprises a first portion (130) having a first shape, wherein the first portion is configured to emit light of a first spectral distribution, S.sub.1, in a first spatial direction, D.sub.1, and a second portion (140) having a second shape, different from the first shape, and the second portion is configured to emit light of a second spectral distribution, S.sub.2, in a second spatial direction, D.sub.2, wherein the first spectral distribution, S.sub.1, is different from the second spectral distribution, S.sub.2, and the first spatial direction, D.sub.1, is different from the second spatial direction, D.sub.2.
Claims
1. A light emitting diode, LED, filament arrangement, comprising at least one LED filament comprising an array of a plurality of light emitting diodes, LEDs, wherein the at least one LED filament comprises a first portion having a first shape, wherein the first portion is configured to emit light of a first spectral distribution, S.sub.1, in a first spatial direction, D.sub.1, and a second portion having a second shape, different from the first shape, wherein the second portion is configured to emit light of a second spectral distribution, S.sub.2, in a second spatial direction, D.sub.2, wherein first spectral distribution, S.sub.1, is different from the second spectral distribution, S.sub.2, and wherein the first spatial direction, D.sub.1, is different from the second spatial direction, D.sub.2, and, wherein the second portion has a spiral, meander, coil or helix shape.
2. The LED filament arrangement according to claim 1, wherein the first portion is configured to emit light with a first color temperature, CT.sub.1, and wherein the second portion is configured to emit light with a second color temperature, CT.sub.2, wherein CT.sub.1≠CT.sub.2.
3. The LED filament arrangement according to claim 2, wherein CT.sub.1>CT.sub.2.
4. The LED filament arrangement according to claim 2, wherein the first and second color temperatures fulfill 300 K<|(CT.sub.1−CT.sub.2)|<1000 K.
5. The LED filament arrangement according to claim 1, wherein the first portion has a flat or disc shape.
6. The LED filament arrangement according to claim 1, wherein the first portion has a twisted, bended or folded shape with respect to the second portion.
7. The LED filament arrangement according to claim 1, wherein the first portion is configured to emit light with a first UV content, and wherein the second portion is configured to emit light with a second UV content, different from the first UV content.
8. The LED filament arrangement according to claim 1, wherein the first portion has a first length, L.sub.1, and the second portion has a second length, L.sub.2, wherein 2L.sub.1<L.sub.2.
9. The LED filament arrangement according to claim 1, wherein the first portion comprises M LEDs and the second portion comprises N LEDs, wherein 2M<N.
10. The LED filament arrangement according to claim 1, wherein the at least one LED filament comprises an encapsulant at least partially enclosing the plurality of LEDs, wherein the encapsulant comprises a luminescent material.
11. The LED filament arrangement according to claim 10, wherein the encapsulant at least partially encloses at least one of the first portion and the second portion, and wherein at least one of a thickness, T.sub.L, of the encapsulant and a concentration, C.sub.L, of the luminescent material in the encapsulant varies over the length of at least one of the first portion and the second portion.
12. The LED filament arrangement according to claim 1, wherein the at least one LED filament comprises a carrier arranged to support the plurality of LEDs, wherein the carrier is light transmissive.
13. The LED filament arrangement according to claim 1, wherein the carrier comprises a first side and a second side, opposite the first side, wherein the plurality of LEDs is arranged on the first side of the carrier, and wherein the at least one LED filament comprises an encapsulant at least partially enclosing at least one of the first side and second side of the carrier, wherein the encapsulant comprises a luminescent material.
14. A lighting device, comprising a LED filament arrangement according to claim 1, a cover comprising an at least partially light-transmissive material, wherein the cover at least partially encloses the LED filament arrangement, and an electrical connection connected to the LED filament arrangement for a supply of power to the plurality of LEDs of the LED filament arrangement.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiment(s) of the invention.
[0030] FIG. 1 shows a LED filament lamp according to the prior art,
[0031] FIG. 2 shows a LED filament arrangement according to an exemplifying embodiment of the present invention,
[0032] FIGS. 3a-3g show LED filaments of a LED filament arrangement according to exemplifying embodiments of the present invention,
[0033] FIGS. 4-6 show LED lighting devices comprising LED filament arrangements according to exemplifying embodiments of the present invention.
DETAILED DESCRIPTION
[0034] FIG. 1 shows a LED filament lamp 10 according to the prior art, comprising a plurality of LED filaments 20. LED filament lamps 10 of this kind are highly appreciated as they are very decorative, as well as providing numerous advantages compared to incandescent lamps such as a longer operational life, a reduced power consumption, and an increased efficiency related to the ratio between light energy and heat energy. LED filament lamps 10 of this kind are able to produce warm white light. However, it is of interest to improve the properties of the light emitted from the LED filaments 20 without impairing the appearance and/or the decorative aspect of the LED filaments 20 and/or the LED filament lamps 10.
[0035] FIG. 2 shows a LED filament arrangement 100 according to an exemplifying embodiment of the present invention. The LED filament arrangement 100 comprises a LED filament 120 (which furthermore may comprise multiple sub-filaments). The LED filament 120 is providing LED filament light and comprises a plurality of LEDs 125 arranged in an array. The plurality of LEDs 125 preferably comprises more than 5 LEDs, more preferably more than 8 LEDs, and even more preferred more than 10 LEDs. The plurality of LEDs 125 may be direct emitting LEDs which provide a color. Preferably, the LED filament 120 has a length L (not shown) and a width W, wherein L>5W. Preferably, the LEDs 125 are arranged on an elongated carrier like for instance a substrate, that may be rigid (made from e.g. a polymer, glass, quartz, metal or sapphire) or flexible (e.g. made of a polymer or metal, e.g. a film or (polyimide) foil). In case the carrier comprises a first major surface and an opposite second major surface, the plurality of LEDs 125 is arranged on at least one of these surfaces. The carrier may be reflective or light transmissive, such as translucent and preferably transparent. The LED filament 120 may further comprise an encapsulant 145 at least partly covering at least part of the plurality of LEDs 125. For example, the encapsulant 145 may (continuously) cover the LEDs 125 of a first portion of the LED filament 120 and/or (continuously) cover the LEDs 125 of a second portion of the LED filament 120. The encapsulant 145 may be a polymer material which may be flexible such as for example a silicone. Further, the plurality of LEDs 125 may be arranged for emitting LED light e.g. of different colors or spectrums. The encapsulant 145 may comprise a luminescent material that is configured to at least partly convert LED light into converted light. The luminescent material may be a light-scattering material, e.g. a polymer matrix comprising BaSO4, Al2O3 and/or TiO2 particles. The luminescent material may be a phosphor such as an inorganic phosphor (e.g. YAG, LuAG, ECAS, KSiF, etc.) and/or quantum dots or rods. The phosphor may further be e.g. a (blue) green/yellow and/or red phosphor. The luminescent material may hereby be configured to convert e.g. UV LED light into blue converted light and/or UV/blue LED into green/yellow and/or red converted light.
[0036] The LED filament 120 in FIG. 2 is arranged in a spiral or helix. The LED filament 120 comprises a first portion 130 and a second portion 140, wherein the first portion 130 is provided at a tip (end) portion of the second portion 140. The first portion 130 has a (first) length which is much smaller than a (second) length of the second portion 140.
[0037] Furthermore, the first portion 130 of the LED filament 120 may have M LEDs and the second portion may comprise N LEDs, wherein e.g. 2M<N. The first portion 130 may be flexible and the second portion 140 may be rigid, or the other way around, i.e. that the first portion 130 may be rigid and the second portion 140 may be flexible.
[0038] The first portion 130 is configured to emit light in a first spatial direction, D.sub.1. Here, the first portion 130 is configured to emit light in a first spatial direction, D.sub.1, which is shown downwards in the orientation of the LED filament 120 in FIG. 2. However, it will be appreciated that the first spatial direction, D.sub.1, may be substantially any spatial direction from the first portion 130. Furthermore, the first portion 130 is configured to emit light of a first spectral distribution, S.sub.1, e.g. a first (color) temperature. For example, the (first) light from the first portion 130 may have a relatively high color temperature, CT.sub.1, and may be directed towards an object such as a table, a painting, etc. (not shown). Furthermore, the first portion 130 has a first shape, which is exemplified as a flat or disc shape.
[0039] The LED filament 120 further comprises a second portion 140 which is configured to emit light in a second spatial direction, D.sub.2. Here, the second portion 140 is configured to emit light in a second spatial direction, D.sub.2, which is indicated sideways with respect to the orientation of the LED filament 120 as shown in FIG. 2. However, it will be appreciated that the second spatial direction, D.sub.2, may be substantially any desired spatial direction from the second portion 140, wherein the second spatial direction, D.sub.2, is different from the first spatial direction, D.sub.1. Furthermore, the second portion 140 is configured to emit light of a second spectral distribution, S.sub.2, e.g. a second (color) temperature, which is different from the first spectral distribution, S.sub.1. For example, the first spectral distribution, S.sub.1, may have a first color point (x1, y1) and the second spectral distribution may have a second color point (x2, y2) different from the first color point. Preferably |(x2−x1)|>0.3 and/or |(y2-yl)|>0.3.
[0040] The (second) light from the second portion 140 may have a relatively low color temperature, such that CT.sub.2<CT.sub.1. Furthermore, the second portion 140 has a second shape, which is exemplified as a spiral or helix.
[0041] The (first) light from the first portion 130 and the (second) light from the second portion 140 may fulfill CT.sub.1>CT.sub.2 and 300 K<|(CT.sub.1−CT.sub.2)<1000 K. Furthermore, the first portion 130 may be configured to emit light with a first UV content, and the second portion may be configured to emit light with a second UV content, different from the first UV content.
[0042] Although not shown in FIG. 2, a thickness of the encapsulant 145 and/or a concentration of the luminescent material in the encapsulant 145 of the LED filament 120 may vary over the length of the first portion 130 and/or the second portion 140.
[0043] FIGS. 3a-3f show LED filaments 120 of a LED filament arrangement according to exemplifying embodiments of the present invention.
[0044] FIG. 3a shows the shape of the first and second portions 130, 140 of the LED filament 120 as depicted in FIG. 2a, i.e. that the first portion 130 comprises a flat shape and is arranged at a tip (end) portion of the helix shaped second portion 140. The light from the first portion 130 is emitted in a first spatial direction, D.sub.1, which is exemplified in a downwards direction, and with a first spectral distribution, S.sub.1. The light from the second portion 140 is emitted in a second spatial direction, D.sub.2, which is exemplified in a circumferential second direction, D.sub.2, with respect to the spiral or helix-shaped second portion 140. The light from the second portion 140 has a second spectral distribution, S.sub.2, different from the first spectral distribution, S.sub.1.
[0045] In FIG. 3b, the first portion 130 of the LED filament 120 comprises a flat shape and is arranged at a tip (end) portion of the second portion 140 of the LED filament 120 which has the shape of a spiral. The light from the first portion 130 is emitted in a first spatial direction, D.sub.1, which is exemplified in an upwards direction, and with a first spectral distribution, S.sub.1. The light from the second portion 140 is emitted in a second spatial direction, D.sub.2, which is exemplified in a circumferential second direction, D.sub.2, with respect to the helix-shaped second portion 140. The light from the second portion 140 has a second spectral distribution, S.sub.2, different from the first spectral distribution, S.sub.1.
[0046] In FIG. 3c, the second portion 140 of the LED filament 120 comprises a wave or saw-tooth shape, wherein two first portions 130a, 130b of the LED filament 120 are arranged at the respective end (tip) portions of the second portion 140. The light from the first portions 130a, 130b is emitted in a respective first spatial direction, D.sub.1, which is exemplified in the downward directions from the first portions 130a, 130b, and with a respective first spectral distribution, S.sub.1. The light from the second portion 140 is emitted in a second spatial direction, D.sub.2, which is exemplified in a circumferential second direction, D.sub.2, with respect to the second portion 140. The light from the second portion 140 has a second spectral distribution, S.sub.2, different from the first spectral distribution, S.sub.1.
[0047] FIG. 3d shows a similar example of the LED filament 120 of FIG. 3c. Here, the ‘periods’ of the wave or saw-tooth shape is somewhat longer than in FIG. 3c. Furthermore, the light from the first portion 130 has a different first spectral distribution (e.g. color temperature, CT.sub.1) compared to that in FIG. 3c.
[0048] In FIG. 3e, the second portion 140 of the LED filament 120 comprises two ‘peaks’, wherein a first portion 130 of the LED filament 120 is arranged between the peaks of the second portion 130. In this example, the LED filament 120 has the shape of a crown. The (first) light from the first portion 130 and the (second) light from the second portion 140 are not indicated in FIG. 3e.
[0049] In FIG. 3f, the LED filament 120 comprises two first portions 130a, 130b, and a U-shaped or arch-shaped second portion 140 arranged between the first portions 130a, 130b. The (first) light from the first portions 130a, 130b and the (second) light from the second portion 140 are not indicated in FIG. 3f.
[0050] In FIG. 3g, the second portion 140 of the LED filament 120 comprises a cylinder or cone-shaped spiral or helix between the two first portions 130a, 130b. The (first) light from the first portions 130a, 130b and the (second) light from the second portion 140 are not indicated in FIG. 3g.
[0051] FIGS. 4a and 4b show a side view and a top view, respectively, of a LED lighting device 300 comprising a LED filament arrangement 100 according to an exemplifying embodiment of the present invention. The lighting device 300 comprises an envelope or cover 310 of light-transmissive material, which preferably is made of glass. The cover 310 encloses the LED filament arrangement 100. The LED lighting device 300 further comprises a threaded cap 104 which is connected to the cover 310. The LED lighting device 300 further comprises an electrical connection 320 connected to the LED filament arrangement 100 for a supply of power to the plurality of LEDs of the LED filament arrangement 100.
[0052] In FIG. 4a, the first portion 130 of the LED filament 120 comprises a flat shape and is arranged at a tip (end) portion of the second portion 140 of the LED filament 120, wherein the second portion 140 has the shape of a helix. The LED filament 120 elongates along the longitudinal axis, A, of the LED lighting device 300. Consequently, the light from the first portion 130 is emitted in a first spatial direction, D.sub.1, which is exemplified in a upwards direction. The light from the second portion 140 is emitted in a second spatial direction, D.sub.2, which is exemplified in a circumferential second direction, D.sub.2, with respect to the helix-shaped second portion 140. Hence, the first spatial direction, D.sub.1, of the light from the first portion 130 of the LED filament 120 is different from the second spatial direction, D.sub.2, of the light from the second portion 140 of the LED filament 120.
[0053] FIG. 4b shows a top view of the LED lighting device 300 in FIG. 4a, and it is also referred to FIG. 4a for an increased understanding. FIG. 4b schematically indicates some of the elements and associated references provided in FIG. 4a, and indicates the emission of the light from the second portion 140 in the second spatial direction, D.sub.2.
[0054] FIGS. 5a, 5b and 5c show a first side view, a second side view and a top view, respectively, of a LED lighting device 300 comprising a LED filament arrangement 100 according to an exemplifying embodiment of the present invention. Similar to FIG. 4a, the first portions 130a, 130b of the LED filament 120 in FIG. 5a each comprises a flat shape and is arranged at respective tip (end) portions of the second portion 140 of the LED filament 120, wherein the second portion 140 has the shape of a helix. In contrast to the LED filament 120 of FIG. 4a, the LED filament 120 in FIG. 5a elongates perpendicular to the longitudinal axis, A, of the LED lighting device 300. Consequently, the light from the first portions 130a, 130b is emitted in a respective first spatial direction, D.sub.1, which is exemplified in an upward direction. The light from the second portion 140 is emitted in a second spatial direction, D.sub.2, which is exemplified in a circumferential second direction, D.sub.2.
[0055] FIG. 5b shows a second side view of the LED lighting device 300 of FIG. 5a, wherein the second side view of FIG. 5b is shown in an angle of 90° with respect to the first side view of FIG. 5a. In FIG. 5b, the light from the first portions 130a, 130b is emitted in a first spatial direction, D.sub.1, which is exemplified in an upward direction, and the light from the second portion 140 is emitted in a second spatial direction, D.sub.2, which is exemplified in a circumferential second direction, D.sub.2.
[0056] FIG. 5c shows a top view of the LED lighting devices in FIGS. 5a and 5b, and it is also referred to FIGS. 5a and 5b for an increased understanding. FIG. 5c schematically indicates the emission of the light from the second portion 140 in the second spatial direction, D.sub.2.
[0057] FIGS. 6a, 6b and 6c show a first side view, a second side view and a top view, respectively, of a LED lighting device 300 comprising a LED filament arrangement 100 according to an exemplifying embodiment of the present invention. In FIG. 6a, the second portion 140 of the LED filament 120 comprises a meander, wave or saw-tooth shape, wherein two first portions 130a, 130b of the LED filament 120 are arranged at the respective end (tip) portions of the second portion 140. The LED filament 120 in FIG. 6a elongates perpendicular to the longitudinal axis, A, of the LED lighting device 300. Consequently, the light from the first portions 130a, 130b is emitted in a respective first spatial direction, D.sub.1, which is exemplified in an upward direction. The light from the second portion 140 is emitted in a second spatial direction, D.sub.2, which is exemplified in a second direction, D.sub.2, as indicated by the arrows.
[0058] FIG. 6b shows a second side view of the LED lighting device 300 of FIG. 6a, wherein the second side view of FIG. 6b is shown in an angle of 90° with respect to the first side view of FIG. 6a. The light from the first portions 130a, 130b is emitted in a first spatial direction, D.sub.1, which is exemplified in an upward direction, and the light from the second portion 140 is emitted in a second spatial direction, D.sub.2, which is exemplified in a second direction, D.sub.2, which constitutes a plane along the longitudinal axis of the LED lighting device 300.
[0059] FIG. 6c, showing a top view of the LED lighting device 300 in FIGS. 6a and 6b, and it is also referred to FIGS. 6a and 6b for an increased understanding. FIG. 6c schematically indicates the emission of the light from the second portion 140 in the second spatial direction, D.sub.2.
[0060] It should be noted that for all exemplifying embodiments of FIGS. 6a, 6b and 6c, the first portion(s) 130 of the LED filament 120 may be arranged at least partly in the second portion 140 of the LED filament 120. Alternatively, the first portion(s) 130 may be arranged outside the second portion 140.
[0061] The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example, one or more of the LED filament(s) 120, the first portion 130 and/or the second portion 140 of the LED filament 120, etc., may have different shapes, dimensions and/or sizes than those depicted/described.
