Abstract
A light emitting diode, LED, filament arrangement (100) comprising at least one LED filament (120) comprising a plurality of light emitting diodes, LEDs, (140). The LED filament arrangement further comprises a plurality of first sections (180) and a plurality of second sections (200), wherein the plurality of first sections (180) is configured to emit light of a first colour temperature, CT.sub.1, and with a first intensity, I.sub.1, during operation, and the plurality of second sections (200) is configured to emit light of a second colour temperature, CT.sub.2, and with a second intensity, 12, during operation, wherein at least one of CT.sub.1CT.sub.2 and I.sub.1I.sub.2 is fulfilled, and wherein at least two second sections of the plurality of second sections are adjacently arranged and arranged at least partially parallel to each other.
Claims
1. A light emitting diode, LED, filament arrangement comprising at least one LED filament comprising a plurality of light emitting diodes, LEDs, a plurality of first sections of the at least one LED filament, wherein the plurality of first sections is configured to emit light of a first colour temperature, CT.sub.1, and with a first intensity, I.sub.1, during operation, and a plurality of second sections of the at least one LED filament, wherein the plurality of second sections is configured to emit light of a second colour temperature, CT.sub.2, and with a second intensity, I.sub.2, during operation, wherein at least one of CT.sub.1CT.sub.2 and I.sub.1I.sub.2 is fulfilled, wherein the plurality of first sections and the plurality of second sections are arranged in an alternating manner along the length of the respective LED filament and at least two second sections of the plurality of second sections are adjacently arranged and arranged at least partially parallel to each other, said LED filament arrangement further comprising an encapsulant at least partially enclosing the plurality of LEDs, wherein the encapsulant comprises at least one of a luminescent material configured to at least partly convert light emitted from the plurality of LEDs and a light scattering material configured to scatter light emitted from the plurality of LEDs, wherein the encapsulant comprises a first encapsulant portion and a second encapsulant portion, wherein at least a first section of the plurality of first sections comprises the first encapsulant portion and at least a second section of the plurality of second sections comprises the second encapsulant portion, and wherein at least one of: the first encapsulant portion comprises a phosphor of a first phosphor type, P.sub.1, and the second encapsulant portion comprises a phosphor of a second phosphor type, P.sub.2, wherein P.sub.1P.sub.2, the first encapsulant portion comprises a first thickness, T.sub.1, and the second encapsulant portion comprises a second thickness, T.sub.2, wherein T.sub.1T.sub.2, and the first encapsulant portion comprises a phosphor with a first phosphor concentration, PC.sub.1, and the second encapsulant portion comprises a phosphor with a second phosphor concentration, PC.sub.2, wherein PC.sub.1PC.sub.2, is fulfilled, and wherein a number of LEDs, dN.sub.1, per unit length, dL.sub.1, of the plurality of first sections, dN.sub.1/dL.sub.1, and a number of LEDs, dN.sub.2, per unit length, dL.sub.2, of the plurality of second sections, dN.sub.2/dL.sub.2, fulfil dN.sub.1/dL.sub.1dN.sub.2/dL.sub.2.
2. The LED filament arrangement according to claim 1, wherein at least one of |CT.sub.1CT.sub.2|>300 K, and one of I.sub.1/I.sub.2<0.8 and I.sub.1/I.sub.2>1.2, is fulfilled.
3. The LED filament arrangement according to claim 1, wherein at least three second sections of the plurality of second sections are adjacently arranged and arranged at least partially parallel to each other.
4. The LED filament arrangement according to claim 1, wherein at least two first sections of the plurality of first sections are adjacently arranged and arranged at least partially parallel to each other.
5. The LED filament arrangement according to claim 1, wherein a width of at least one first section of the plurality of first sections, W.sub.1, and a width of at least one second section of the plurality of second sections, fulfils W.sub.2<W.sub.1.
6. The LED filament arrangement according to claim 1, wherein a length of at least one second section of the plurality of second sections, L.sub.2, and a length of at least one first section of the plurality of first sections, L.sub.1, fulfils L.sub.2<L.sub.1.
7. The LED filament arrangement according to claim 1, wherein a length of the at least one second section of the plurality of second sections, L.sub.2, fulfils L.sub.2<3 cm.
8. The LED filament arrangement according to claim 1, further comprising a carrier arranged to support the at least one LED filament, wherein the at least one LED filament is arranged on the carrier.
9. The LED filament arrangement according claim 8, wherein at least one of the carrier and the at least one LED filament is flexible.
10. The LED filament arrangement according to claim 1, wherein the at least one LED filament is arranged in at least one of a linear configuration, a meander configuration, a spiral configuration and a sinusoidal configuration.
11. 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 at least one LED filament, and an electrical connection connected to the at least one LED filament for a supply of power to the plurality of LEDs of the at least one LED filament.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) 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.
(2) FIG. 1 shows a LED filament lamp 10 according to the prior art.
(3) FIG. 2a shows a schematic view of at least one LED filament of a LED filament arrangement according to exemplifying embodiments of the present invention.
(4) FIG. 2b shows a schematic view of at least one LED filament of a LED filament arrangement according to exemplifying embodiments of the present invention.
(5) FIGS. 3a-3d schematically show LED filament arrangements according to exemplifying embodiments of the present invention.
(6) FIGS. 4a-4b show schematic views of a cross-section of at least one LED filament of a LED filament arrangement according to exemplifying embodiments of the present invention.
(7) FIG. 5 shows a lighting device comprising a LED filament arrangement according to an exemplifying embodiment of the present invention.
DETAILED DESCRIPTION
(8) 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.
(9) FIG. 2a-2b shows a LED filament arrangement 100 according to an exemplifying embodiment of the present invention. The LED filament arrangement 100 comprises at least one LED filament 120. Here, the LED filament arrangement 100 is exemplified as comprising three LED filaments 120, but it should be noted that the number of LED filaments 120 is arbitrary. The LED filaments 120 comprise a plurality of LEDs 140. The LED filaments 120 further comprise a plurality of first sections 180 and a plurality of second sections 200. In FIGS. 2a-2b, the plurality of first sections 180 and the plurality of second sections 200 are arranged in an alternating manner along the length of the respective LED filament 120. In FIGS. 2a-2b, at least two second sections of the plurality of second sections 200 are adjacently arranged and arranged at least partially parallel to each other.
(10) In FIG. 2a, the plurality of first sections 180 are configured to emit light of a first intensity, I.sub.1. The plurality of second sections 200 are configured to emit light of a second intensity, I.sub.2, wherein I.sub.1I.sub.2 is fulfilled during operation of the LED filament arrangement 100. For example, I.sub.1/I.sub.2<0.8 may be fulfilled, and preferably I.sub.1/I.sub.2<0.5. Alternatively, I.sub.1/I.sub.2>1.2 may be fulfilled, and preferably I.sub.1/I.sub.2>2.
(11) In FIG. 2a, the concentration of LEDs 140 in the plurality of first sections 180 and the plurality of second sections 200 differ. For example, the concentration of LEDs 140 in the plurality of second sections 200 per unit length thereof is higher than in the plurality of first sections 180, thus providing a more intense emitted light. The concentration of LEDs 140 may be described as a number of LEDs 140, dN.sub.1, per unit length, dL.sub.1, of the plurality of first sections 180, dN.sub.1/dL.sub.1, and a number of LEDs 140, dN.sub.2, per unit length, dL.sub.2, of the plurality of second sections 200, dN.sub.2/dL.sub.2, wherein dN.sub.1/dL.sub.1dN.sub.2/dL.sub.2 is fulfilled in FIG. 2a. For example, the ratio between dN.sub.1/dL.sub.1 and dN.sub.2/dL.sub.2 may be <0.8 or >1.2. Furthermore, a first width, W.sub.1 (not shown) of the plurality of first sections 180, and a second width, W.sub.2 (not shown) of the plurality of second sections 200, may fulfil W.sub.2<W.sub.1.
(12) The LED filament(s) 120 of the LED filament arrangement 100 in FIG. 2a further comprises an encapsulant 210 at least partially enclosing the plurality of LEDs 140. The encapsulant 210 comprises a luminescent material configured to at least partly convert light emitted from the plurality of LEDs 140 and/or a light scattering material configured to scatter light emitted from the plurality of LEDs 140. It will be appreciated that the plurality of first sections 180 and the plurality of second sections 200 can have, at least partially, a different encapsulant 210 with different characteristics. For example, the encapsulant 210 of the first sections 180 may comprise a phosphor of a first phosphor type, P.sub.1, a first thickness, T.sub.1, and a first phosphor concentration, PC.sub.1, and the encapsulant 210 of the second sections 200 (not shown) may comprise a phosphor of a second phosphor type, P.sub.2, a second thickness, T.sub.2, and a second phosphor concentration, PC.sub.2, wherein P.sub.1P.sub.2, T.sub.1T.sub.2 and/or PC.sub.1PC.sub.2.
(13) In FIG. 2a, the plurality of second sections 200 are adjacently arranged and substantially parallel to each other. The plurality of second sections 200 are arranged to form a linear pattern, wherein the linear pattern is extending in a direction substantially perpendicular to the direction of extension of the at least one LED filament 120.
(14) In FIG. 2b, the plurality of first sections 180 are configured to emit light of a first colour temperature, CT.sub.1. The plurality of second sections 200 are configured to emit light of a second colour temperature, CT.sub.2, wherein CT.sub.1CT.sub.2 is fulfilled during operation of the LED filament arrangement 100. For example, |CT.sub.1CT.sub.2|>300 K may be fulfilled. Preferably, |CT.sub.1CT.sub.2|>500 K, more preferably |CT.sub.1CT.sub.2|>600 K and most preferably |CT.sub.1CT.sub.2|>700 K. According to another example, in order to limit the difference in colour temperature, |CT.sub.1CT.sub.2|<2500 K may be fulfilled. Preferably, |CT.sub.1CT.sub.2|<2000 K, more preferably |CT.sub.1CT.sub.2|<1500 K and most preferably |CT.sub.1CT.sub.2|<1200 K.
(15) In FIG. 2b, the plurality of second sections 200 are adjacently arranged and at least partially parallel to each other, wherein the plurality of second sections 200 are arranged to form a linear pattern. The linear pattern formed by the plurality of second sections 200 in FIG. 2b is extending in a direction diagonally to the direction of extension of the at least one LED filament 120. The linear pattern of the plurality of second sections 200 in FIG. 2B can be seen as a line crossing the at least one LED filament 120 diagonally.
(16) The LED filament(s) 120 of the LED filament arrangements 100 of FIGS. 2a-b may further comprise an encapsulant (not shown) at least partly covering at least part of the plurality of LEDs 140. For example, the encapsulant may (continuously) cover the LEDs 140 of one or more first sections 180 of the LED filament(s) 120 and/or (continuously) cover the LEDs 140 of one or more second sections 200 of the LED filament(s) 120. The encapsulant may be a polymer material which may be flexible such as for example a silicone. Further, the plurality of LEDs 140 may be arranged for emitting LED light e.g. of different colours or spectrums. The encapsulant 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 BaSO.sub.4, Al.sub.2O.sub.3 and/or TiO.sub.2 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. The LED filament(s) 120 may comprise multiple sub-filaments.
(17) FIGS. 3a-3d show schematic views of a LED filament arrangement 100 according to an exemplifying embodiment of the present invention. The LED filament arrangement 100 comprises at least one LED filament 120. The LED filament 120 comprises a plurality of first sections 180 and a plurality of second sections 200, wherein the plurality of second sections 200 are aligned. Each second section of the plurality of second sections 200 is adjacently arranged to at least one second section, wherein the at least two second sections are arranged at least partially parallel to each other. The plurality of second sections 200 may be arranged to align in one or more linear patterns, wherein the at least one linear pattern of second sections may be straight or curved. In FIG. 3a-3d the emitted light from the plurality of second sections 200 is different than the emitted light from the plurality of first sections 180. The plurality of second sections 200 may also be configured to emit no light at all.
(18) In FIG. 3a, the LED filament arrangement 100 comprises at least one LED filament 120. The at least one LED filament 120 is arranged in a linear configuration, wherein the plurality of second sections 200 is arranged to form a pattern comprising a continuous line extending in a direction at least partially perpendicular to the direction of extension of the at least one LED filament 120.
(19) In FIG. 3b, the LED filament arrangement 100 comprises at least one LED filament 120. The at least one LED filament 120 is arranged in a spiral configuration, wherein the plurality of second sections 200 is arranged to form a pattern comprising two continuous lines, wherein the two continuous lines cross each other in the centre of the LED filament arrangement 100.
(20) In FIG. 3c, the LED filament arrangement 100 comprises at least one LED filament 120. The at least one LED filament 120 is arranged in a sinusoidal configuration, wherein the plurality of second sections 200 is arranged to form a pattern comprising two continuous lines.
(21) In FIG. 3d, the LED filament arrangement 100 comprises at least one LED filament 120. The at least one LED filament 120 is arranged in a meander configuration, wherein the plurality of second sections 200 is arranged to form a pattern comprising a plurality of continuous lines, wherein the plurality of continuous lines are substantially perpendicular to the direction of extension of the meander pattern. The meander pattern is created by the arrangement of the at least one LED filament 120 in a meander configuration. In FIG. 3d the LED filament arrangement 100 further comprises a carrier 160. It is to be understood that the carrier 160 may have a different size and different dimensions than shown in FIG. 3d, e.g. the carrier may have the shape of the contour of the LED filament arrangement 100. In other words, the shape of the carrier 160 may be similar to the shape of the LED filament arrangement 100. The carrier 160 may be a heat sink, wherein the carrier 160, in that case, is configured to dissipate heat from the at least one LED filament 120 during operation of the LED filament arrangement.
(22) FIG. 4a shows a schematic view of a cross section of at least one LED filament 120 of the LED filament arrangement according to an exemplifying embodiment of the present invention. The at least one LED filament 120 comprises a first encapsulant portion 212. The first encapsulant portion 212 at least partially encloses the LEDs 140. The first encapsulant portion 212 has a first thickness, T.sub.1. The first encapsulant portion 212 further comprises a phosphor of a first phosphor type, P.sub.1, and of a first phosphor concentration, PC.sub.1.
(23) FIG. 4b shows a schematic view of a cross section of at least one LED filament 120 of the LED filament arrangement according to an exemplifying embodiment of the present invention. The at least one LED filament 120 comprises a second encapsulant portion 214. The second encapsulant portion 214 at least partially encloses the LEDs 140. The second encapsulant portion 214 has a second thickness, T.sub.2. The second encapsulant portion 214 further comprises a phosphor of a second phosphor type, P.sub.2, and of a second phosphor concentration, PC.sub.2. In FIGS. 4a and 4b, the first and second thicknesses, T.sub.1, T.sub.2, of the first and second encapsulant portions, 212, 214, respectively, fulfill T.sub.1T.sub.2. For example, the ratio between T.sub.1 and T.sub.2 may be <0.8 or >1.2. Furthermore, the second phosphor type, P.sub.2, and the second phosphor concentration, PC.sub.2, of the second encapsulant portion 214 may differ from the first phosphor type, P.sub.1, and the first phosphor concentration, PC.sub.1, of the first encapsulant portion 212. For example, the ratio between PC.sub.1 and PC.sub.2 may be <0.8 or >1.2.
(24) FIG. 5 schematically shows a lighting device 300 according to an embodiment of the present invention. The lighting device 300 comprises a LED filament arrangement 100 according to any one of the previously described embodiments. The lighting device 300 further comprises a cover 310, which is exemplified as being bulb-shaped. The cover 310 may comprise an at least partially light transmissive (e.g. transparent) material and at least partially encloses the LED filament arrangement 100. The 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.
(25) 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 may have different shapes, dimensions and/or sizes than those depicted/described.
