LED filament arrangement

Abstract

A LED filament arrangement (100) is provided, comprising a first LED filament (110a) configured to emit first LED filament light (115a) and comprising a plurality of first LEDs (130a) configured to emit first LED light (150a) having a first peak emission wavelength, λ1, in a first blue wavelength range of 430 - 500 nm, and a second LED filament (110b) configured to emit second LED filament light (115b) and comprising a plurality of second LEDs (130b) configured to emit second LED light (150b) having a second peak emission wavelength, λ2, in a second blue wavelength range of 400 - 490 nm, and a plurality of third LEDs (130c) configured to emit third LED light (150c) having a third peak emission wavelength, λ3, in a green wavelength range of 500 - 540 nm, and a controller (200) configured to individually control the first LED light, the second LED light, and the third LED light.

Description

[0001] 2024PF80122

[0002] 1

[0003] LED filament arrangement

[0004] FIELD OF THE INVENTION

[0005] The present invention generally relates to a light emitting diode, LED, filament arrangement. More specifically, the present invention relates to a LED filament arrangement arranged to provide white and colored light upon operation.

[0006] BACKGROUND OF THE INVENTION

[0007] The use of light emitting diodes, LEDs, for illumination purposes continues to attract attention. Compared to incandescent lamps, fluorescent lamps, neon tube lamps, etc., LEDs provide numerous advantages such as a longer operational life, a reduced power consumption, and an increased efficiency related to the ratio between light energy and heat energy.

[0008] Many LED filament lamps or devices in the prior art comprise LED filaments for achieving the above-mentioned advantages, as well as achieving aesthetically appealing lamps. In particular, spiral-shaped red-green-blue-white (RGBW) LED filaments have become the dominant LED filament architecture for LED filaments providing white and colored light.

[0009] However, customer feedback has indicated that these types of RGBW LED filaments of the prior art often suffer from a deteriorated aesthetical appearance, and in particular that these LED filaments are too wide. It should be noted that attempts (only) focused on augmenting this aesthetical aspect may lead to a risk that the efficiency and / or luminous flux of the light emitted from LED filament lamp becomes non-optimal. Hence, it is of interest to further improve the visual appearance of the LED filament lamps whilst ensuring the light-emitting properties of the light emitted from the LED filaments.

[0010] It is an object of the present invention to provide, or even augment, the advantageous functionalities of LED filament lamps concerning the properties of the light emission from the LED filaments, whilst providing a desired aesthetical appearance and / or decorative aspect of the LED filaments and / or the LED filament lamps.

[0011] WO 2024 / 160544 relates to an LED filament, comprising: a carrier; a plurality of first blue LEDs arranged on the carrier and adapted to emit first blue light;— a first 2024PF80122

[0012] 2 elongated encapsulant covering the first blue LEDs and at least part of the carrier, wherein the first elongated encapsulant comprises a first luminescent material configured to convert at least part of the first blue light into first converted light; and a top surface on or over the first elongated encapsulant, wherein the LED filament further comprises: - a string of second blue LEDs arranged on top of the top surface of the LED filament and adapted to emit second blue light, wherein light output surfaces of the second blue LEDs are facing away from the LED filament.

[0013] SUMMARY OF THE INVENTION

[0014] It is of interest to explore the possibility of combining one or more of the numerous advantages of LED filament arrangements comprising LEDs, whilst improving the properties of the light emission from the LED filaments and improving the appearance and / or the decorative aspect of the LED filaments and / or the LED filament lamps.

[0015] This and other objects are achieved by providing a LED filament arrangement having the features in the independent claim. Preferred embodiments are defined in the dependent claims.

[0016] According to the present invention, there is provided a light emitting diode, LED, filament arrangement, configured to emit LED filament arrangement light. The LED filament arrangement comprises a first LED filament configured to emit first LED filament light. The first LED filament comprises a first elongated carrier, a plurality of first LEDs arranged on a first major surface of the first elongated carrier, wherein the plurality of first LEDs is configured to emit first LED light having a first peak emission wavelength, I, in a first blue wavelength range of 430 - 500 nm, and a first encapsulant covering (e.g. at least partly enclosing) the plurality of first LEDs and at least part of the first major surface of the first elongated carrier. The LED filament arrangement further comprises a second LED filament configured to emit second LED filament light. The second LED filament comprises a second elongated carrier, and a plurality of second LEDs arranged on a first major surface of the second elongated carrier, wherein the plurality of second LEDs is configured to emit second LED light having a second peak emission wavelength, X2, in a second blue wavelength range of 400 - 490 nm. The second LED filament further comprises a plurality of third LEDs arranged on the first major surface of the second elongated carrier, wherein the plurality of third LEDs is configured to emit third LED light having a third peak emission wavelength, X3, in a green wavelength range of 500 - 540 nm. The second LED filament 2024PF80122

[0017] 3 further comprises a second encapsulant covering (e.g. at least partly enclosing) the plurality of second LEDs and the plurality of third LEDs and covering at least part of the first major surface of the second elongated carrier, wherein the second encapsulant comprises luminescent material configured to at least partly convert the emitted second LED light into converted light having a fourth peak emission wavelength, 4, in a red wavelength range of 600 - 675 nm. The LED filament arrangement further comprises a controller connected to the plurality of first LEDs, the plurality of second LEDs and the plurality of third LEDs, wherein the controller is configured to individually control emission of the first LED light, the second LED light, and the third LED light.

[0018] Thus, the present invention is based on the idea of providing a LED filament arrangement with two (first and second) LED filaments and three (first, second and third) pluralities of LEDs, wherein the LED filament is configured to emit white light and colored (e.g. blue, green, red) light. Hereby, the construction of the LED filament is slim, thereby improving the visual appearance of the LED filament arrangement whilst optimizing the efficiency and / or luminous flux of the LED filament arrangement light.

[0019] It will be appreciated that the pair of (first and second) LED filaments as grouped or clustered of the LED filament arrangement emit light for an improved appearance whilst taking into account efficiency and light distribution. By the LED filament arrangement including these LED filaments, the properties of the light emission from the LED filaments are improved, whilst providing a desired aesthetical appearance and / or decorative aspect of the LED filaments.

[0020] The present invention is advantageous by its achievement of lighting efficiency and aesthetical appearance. Albeit prior art arrangements may use LED filaments in a single lamp for trying to improve the efficiency, the LED filament appearance of the lamp may be lost. In contrast, the LED filaments of the present invention overcomes this problem by its decorative light emission whilst taking into account efficiency and light distribution.

[0021] The present invention is further advantageous in that the LED filament arrangement may achieve a relatively slim line LED light emission, an improved mixing of the LED light and / or less spottiness of the LED light compared to prior art arrangements.

[0022] The present invention is further advantageous in that the numerous advantages of using LED technology may be combined with the attractiveness and the appealing properties of the LED filament arrangement as disclosed. 2024PF80122

[0023] 4

[0024] The present invention is further advantageous in that the LED filament arrangement of the present invention comprises relatively few components. The low number of components is advantageous in that the LED filament arrangement is relatively inexpensive to fabricate. Moreover, the low number of components of the LED filament arrangement implies an easier recycling, especially compared to devices or arrangements comprising a relatively high number of components which impede an easy disassembling and / or recycling operation.

[0025] There is provided a LED filament arrangement, configured to emit LED filament arrangement light. The LED filament arrangement comprises a first LED filament configured to emit first LED filament light. The first LED filament comprises a first elongated carrier, and a plurality of first LEDs arranged on a first major surface of the first elongated carrier. The plurality of first LEDs may be arranged in a linear array. By the term “array”, it is here meant a linear arrangement or chain of LEDs, or the like. The first elongated carrier may, for instance, be 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 foil). The first elongated carrier may be reflective or light transmissive, such as translucent and preferably transparent. Preferably, the first LED filament has a length, L, and a width, W, wherein L > 5W. The first LED filament may be arranged in a straight configuration or in a non-straight configuration such as for example a curved configuration, a 2D / 3D spiral or a helix. The plurality of first LEDs is configured to emit first LED light having a first peak emission wavelength, I, in a first blue wavelength range of 430 - 500 nm. The first LED filament further comprises a first encapsulant covering the plurality of first LEDs and at least part of the first major surface of the first elongated carrier. By the term “first encapsulant”, it is here meant an (elongated) material, element, arrangement, or the like, which in the present context is configured or arranged to at least partially surround, encapsulate and / or enclose the first elongated carrier and the plurality of first LEDs.

[0026] The first encapsulant may be a polymer material which may be flexible such as for example a silicone. The luminescent material of the first encapsulant may be a phosphor such as an inorganic phosphor and / or quantum dots or rods. The first encapsulant may be a first elongated encapsulant. The second encapsulant may be a second elongated encapsulant.

[0027] The LED filament arrangement further comprises a second LED filament configured to emit second LED filament light. The second LED filament comprises a second elongated carrier, a plurality of second LEDs arranged on a first major surface of the second 2024PF80122

[0028] 5 elongated carrier, wherein the plurality of second LEDs is configured to emit second LED light having a second peak emission wavelength, 2, in a second blue wavelength range of 400 - 490 nm, and a plurality of third LEDs arranged on the first major surface of the second elongated carrier, wherein the plurality of third LEDs is configured to emit third LED light having a third peak emission wavelength, 3, in a green wavelength range of 500 - 540 nm. Analogously with the component(s) and / or feature(s) of the first LED filament, the second elongated carrier may, for instance, be 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 foil). The second elongated carrier may be reflective or light transmissive, such as translucent and preferably transparent. Preferably, the second LED filament has a length, L, and a width, W, wherein L > 5W. The second LED filament may be arranged in a straight configuration or in a non-straight configuration such as for example a curved configuration, a 2D / 3D spiral or a helix. The second LED filament further comprises a second encapsulant covering the plurality of second LEDs and the plurality of third LEDs and covering at least part of the first major surface of the second elongated carrier, wherein the second encapsulant comprises luminescent material configured to at least partly convert the emitted second LED light into converted light having a fourth peak emission wavelength, 4, in a red wavelength range of 600 - 675 nm. Analogously with the first encapsulant of the first LED filament, it is, by the term “second encapsulant”, meant an (elongated) material, element, arrangement, or the like, which in the present context is configured or arranged to at least partially surround, encapsulate and / or enclose the second elongated carrier and the plurality of second and third LEDs. The second encapsulant may be a polymer material which may be flexible such as for example a silicone. The luminescent material of the second encapsulant may be a phosphor such as an inorganic phosphor and / or quantum dots or rods. The luminescent material may be configured / chosen such that less than 10%, preferably less than 5%, more preferably less than 5%, most preferably less than 2%, e.g. 1% or 0% of the third LED light is converted.

[0029] It should be noted that the first encapsulant may not cover the plurality of second LEDs and the plurality of third LEDs. Analogously, the second encapsulant may not cover the plurality of first LEDs.

[0030] The LED filament arrangement further comprises a controller connected to the plurality of first LEDs, the plurality of second LEDs, and the plurality of third LEDs, wherein the controller is configured to individually control emission of the first LED light, the second LED light, and the third LED light. By “controller”, it is here meant any device, unit, or the 2024PF80122

[0031] 6 like, which is able to (individually / respectively) control the emission of the first, second and third LED lights, either by wire or via wireless technology.

[0032] According to an embodiment of the present invention, the controller may be configured to operate in (i) a first operational mode, comprising emission of the first LED light, non-emission of the second LED light, and non-emission of the third LED light, whereby the emitted LED filament arrangement light is blue light, (ii) a second operational mode, comprising non-emission of the first LED light, non-emission of the second LED light, and emission of the third LED light, whereby the emitted LED filament arrangement light is green light, (iii) a third operational mode, comprising non-emission of the first LED light, emission of the second LED light, and non-emission of the third LED light, whereby the emitted LED filament arrangement light is red light, and optionally (iv) a fourth operational mode, comprising emission of the first LED light, emission of the second LED light, and emission of the third LED light, whereby the emitted LED filament arrangement light is white light having a correlated color temperature, CCT, in a range of 1500 - 6500 K and a color rendering index, CRI, of at least 80. Hence, the controller is configured to operate in one of, or in at least one of, the first, second, third and / or fourth operational mode(s) (i)-(iv). By the ability of the controller to control emission or non-emission of each of the first, second and third LED lights, the emitted LED filament arrangement light is blue, green, red and / or white light. By the term “non-emission”, it is hereby meant less than 5% or less than 2%, e.g. 1% or 0%, of the emitted LED filament arrangement light. The present embodiment is advantageous in that the controller may conveniently and efficiently control the emission(s) of the LED light(s) via the operational mode(s), in order to achieve a desired color, consequently leading to an aesthetically appealing LED filament arrangement light. Furthermore, by the ability of the controller to tune or set the correlated color temperature, CCT, and the color rendering index, CRI, the aesthetic effect of the LED filament arrangement light may be augmented even further.

[0033] According to an embodiment of the present invention, the luminescent material of the second encapsulant may comprise a first red phosphor of the type M’xM2-2xAX6 doped with tetravalent manganese, wherein M’ comprises an alkaline earth cation, M comprises an alkaline cation, and x is selected from the range of 0 - 1, wherein A comprises a tetraval ent cation, wherein X comprises a monovalent anion, at least comprising fluorine. Relevant alkaline cations (M) are sodium (Na), potassium (K) and rubidium (Rb). Optionally, also lithium and / or cesium may be applied. In a preferred example, M comprises at least 2024PF80122

[0034] 7 potassium. In yet another example, M comprises at least rubidium. The phrase “wherein M comprises at least potassium” indicates for instance that of all M cations in a mole M’XM2- 2XAXe , a fraction comprises K+and an optionally remaining fraction comprises one or more other monovalent (alkaline) cations (see also below). In another preferred example, M comprises at least potassium and rubidium. Optionally, the M’xM2-2xAX6 luminescent material has the hexagonal phase. In yet another example, the M’xM2-2XAX6 luminescent material has the cubic phase. For x=0, the composition is M2AX6.

[0035] Relevant alkaline earth cations (M’) are magnesium (Mg), strontium (Sr), calcium (Ca) and barium (Ba), especially one or more of Sr and Ba.

[0036] The term “tetravalent manganese” refers to Mn4+. This is a well-known luminescent ion. In the formula as indicated above, part of the tetravalent cation A (such as Si) is being replaced by manganese. Hence, M’xM2-2XAX6 doped with tetravalent manganese may also be indicated as M’xM2-2XAi-mMnmX6. The mole percentage of manganese, i.e. the percentage it replaces the tetravalent cation A will in general be in the range of 0.1-15 %, especially 1-12 %, i.e. m is in the range of 0.001-0.15, especially in the range of 0.01-0.12.

[0037] As indicated above, X relates to a monovalent anion, but at least comprises fluorine. Other monovalent anions that may optionally be present may be selected from the group consisting of chlorine (Cl), bromine (Br), and iodine (I).

[0038] The use of M’xM2-2XAX6 luminescent material is particularly advantageous in that it does not absorb green light. Hence, in one mode, an appealing green light may be provided, and in another mode, an appealing red light may be provided. According to an example, M’xM2-2XAX6 comprises K^SiFe (indicated herein also as KSiF system). As indicated above, in another preferred example, M’xM2-2XAX6 comprises KRbSiFe (herein also indicated as K,Rb system). As indicated above, part of silicon is replaced by manganese (i.e. the formula may also be described as K2Sii-mMnmF6 or KRbSii-mMnmF6, with m as indicated above, or as KRbSiFe:Mn and K2SiFe:Mn, respectively). As manganese replaces part of a host lattice ion and has a specific function, it is also indicated as “dopant” or “activator”. Hence, the hexafluorosilicate is doped or activated with manganese (Mn4+).

[0039] In specific examples, the luminescent material may comprise (K,Rb)2SiFe:Mn4+. Alternatively or additionally, in examples the third luminescent material may comprise K2SiFe:Mn4+. Alternatively or additionally, in examples the third luminescent material may comprise K2TiFe:Mn4+. In examples, the third luminescent material may 2024PF80122

[0040] 8 comprise K2(Si,Ti)Fe:Mn4+. As can be derived from the above, “Si,Ti” may indicate one or more of Si and Ti.

[0041] According to an embodiment of the present invention, at least 80% of the luminescent material in the second encapsulant may be the first red phosphor.

[0042] According to an example of the present invention, at least 80% of the luminescent material in the second encapsulant may be K2SiF6:Mn<4+>, K2GeF6:Mn<4+>, or K2TiF6:Mn<4+>.

[0043] According to an embodiment of the present invention, the first elongated carrier and the second elongated carriers may be light-transmissive, the first encapsulant at least partially covers a second major surface, opposite the first major surface, of the first elongated carrier, and the second encapsulant at least partially covers a second major surface, opposite the first major surface, of the second elongated carrier. The present embodiment is advantageous in that a substantially omnidirectional light distribution from the LED filament arrangement may be obtained, whereby this optimal light distribution even further contributes to the optical performance and / or aesthetical attractiveness of the LED filament arrangement and / or the LED filament arrangement light.

[0044] According to an embodiment of the present invention, the first LED filament and the second LED filament may be arranged in parallel, and wherein a first normal, Ni, of the first major surface of the first elongated carrier and a second normal, N2, of the first major surface of second elongated carrier, are, one of parallel to each other, and arranged with an angle, a, between the first normal, Ni, and the second normal, N2, wherein the angle, a, is in a range of 20° - 70°. Hence, the first and second LED filaments are (adjacently) arranged in parallel, and the first and second normals, Ni, N2, are either parallel to each other or arranged with an angle, a, therebetween, wherein the angle, a, is in a range of 20° - 70°. The present embodiment is advantageous in that the light distribution and / or attractiveness of the LED filament arrangement (light) may be increased even further. For example, in case the first and second LED filaments are arranged so that the first and second normals, Ni, N2, are parallel to each other, the first, second and third LED lights are emitted and directed in parallel, which may be beneficial for directing the LED filament arrangement light in a (major) direction. In case the angle, a, between the first normal, Ni, and the second normal, N2, is in a range of 20° - 70°, such as e.g. 30° - 60°, the direction of the first LED light (from the first LED filament) is different from the second and third LED lights (from the second LED filament). Consequently, a desired lighting distribution and / or distribution of color(s) may be achieved 2024PF80122

[0045] 9 by this arrangement of the first and second LED filaments with respect to each other. The present embodiment is hereby advantageous in that the slim construction of the LED filament improves the visual appearance of the LED filament arrangement whilst providing a customization of the emitted LED filament arrangement light.

[0046] According to an embodiment of the present invention, the first LED filament and the second LED filament may be arranged in abutment with each other. In other words, the first and second LED filaments may be arranged adjacently in parallel so that the first and second LED filaments are in contact. The present embodiment is advantageous in that the LED filament becomes even slimmer, consequently augmenting the aesthetical attractiveness of the LED filament arrangement.

[0047] According to an embodiment of the present invention, the first LED filament and the second LED filament may be arranged at a distance, d, from each other. In other words, the first and second LED filaments may be arranged adjacently in parallel, and wherein the first and second LED filaments are separated along their lengths by a distance, d (i.e. the first and second LED filaments not being in contact).

[0048] According to an embodiment of the present invention, a reflector may be arranged between the first LED filament and the second LED filament. Hence, the first and second LED filaments are arranged at a distance, d, from each other, and a reflector is arranged in this gap between the first and second LED filaments. The reflector may hereby reflect the (first) blue LED light emitted from the first LED filament, and also reflect the (second) blue light, the (third) green light, and / or the (converted) red light emitted from the second LED filament. The present embodiment is particularly advantageous concerning a separation of the first LED light from the second, third and fourth LED lights.

[0049] According to an embodiment of the present invention, the first LED filament and the second LED filament may be arranged in a spiral shape. Hence, the first and second LED filaments may be spirally arranged around an axis. For example, the first and second LED filaments may be arranged in abutment with each other and arranged in a spiral shape. The present embodiment is advantageous in that the LED filament arrangement in this spiral shape of the LED filaments is particularly attractive.

[0050] According to an embodiment of the present invention, the second blue wavelength range may be 420 - 475 nm. The plurality of first LEDs is hereby configured to emit second LED light having a second peak emission wavelength, 2, in a second blue wavelength range of 420 - 475 nm. The obtained effect is improved light conversion e.g. a 2024PF80122

[0051] 10 higher light conversion rate. The reason is that luminescent material can be effectively excited with light in this wavelength range (i.e. in this wavelength range of visible light the excitation spectrum of the luminescent material has a peak).

[0052] According to an embodiment of the present invention, the first blue wavelength range may be 480 - 500 nm. The plurality of first LEDs is hereby configured to emit first LED light having a first peak emission wavelength, I, in a first blue wavelength range of 480 - 500 nm. The present embodiment is advantageous in that there is only a very small, or almost no crosstalk. In other words, the present embodiment is advantageous in that there is only a very small, or almost no, absorption of first LED light i.e. blue light by luminescent material in the second encapsulant, especially in case (the luminescent material of) the second encapsulant comprises a first red phosphor of the type M’xM2-2xAX6 doped with tetravalent manganese, wherein M’ comprises an alkaline earth cation, M comprises an alkaline cation, and x is selected from the range of 0 - 1, wherein A comprises a tetraval ent cation, wherein X comprises a monovalent anion, at least comprising fluorine e.g. K2SiF6:Mn<4+>, K2GeF6:Mn<4+>, or K2TiF6:Mn<4+>.

[0053] According to an embodiment of the present invention, the green wavelength range may be 510 - 540 nm. The plurality of third LEDs is hereby configured to emit third LED light having a third peak emission wavelength, X3, in a green wavelength range of 510 - 540 nm. The present embodiment is advantageous in that there is only a very small, or substantially no, conversion of the green light by the luminescent material in the second encapsulant, especially in case (the luminescent material in) the second encapsulant comprises a first red phosphor of the type M’xM2-2xAX6 doped with tetraval ent manganese, wherein M’ comprises an alkaline earth cation, M comprises an alkaline cation, and x is selected from the range of 0 - 1, wherein A comprises a tetravalent cation, wherein X comprises a monovalent anion, at least comprising fluorine e.g. K2SiF6:Mn<4+>, K2GeF6:Mn<4+>, or K2TiF6:Mn<4+>. In other words, in this way, high quality / pure green light can be generated.

[0054] In embodiments, the second blue wavelength range may be 420 - 475 nm, the first blue wavelength range may be 480 - 500 nm, and / or the green wavelength range may be 510 - 540 nm.

[0055] In embodiments, the luminescent material of the second encapsulant may comprise a second red phosphor, wherein the second red phosphor comprises a nitride phosphor and / or an oxynitride phosphor. The obtained effect is improved conversion. The 2024PF80122

[0056] 11 reason is that relatively to the M’xM2-2xAX6 luminescent material, an (oxy)nitride phosphor has a very high / higher absorption for (420 nm - 475 nm) blue light.

[0057] In embodiments, the first encapsulant is free from a luminescent material. In this context, the wording ‘free from’ means no or less than 0.5 v / v% luminescent material.

[0058] According to an embodiment of the present invention, the concentration of the luminescent material in the second encapsulant may be in a range of 3 - 15 v / v%. The present embodiment is advantageous in that the volume percentage range of 3 - 15 v / v% of the concentration of the luminescent material in the second encapsulant represents an optimum in conversion of the second (blue) LED light whilst the third (green) LED light can escape well.

[0059] According to an embodiment of the present invention, there is provided a lamp comprising the LED filament arrangement according to any one of the preceding embodiments. The lamp further comprises a cover comprising an at least partially transparent material, wherein the cover at least partially encloses the LED filament arrangement, and a connector electrically connected to the LED filament arrangement for a supply of power to the plurality of first LEDs, the plurality of second LEDs, and the plurality of third LEDs. The present embodiment is advantageous in that the lamp, comprising the LED filament arrangement, combines the aspects of a desired light emission and aesthetical appearance provided via the LED filament arrangement and / or via the feature(s) of the lamp.

[0060] Further objectives of, features of, and advantages with, the present invention will become apparent when studying the following detailed disclosure, the drawings and the appended claims. Those skilled in the art will realize that different features of the present invention can be combined to create embodiments other than those described in the following.

[0061] BRIEF DESCRIPTION OF THE DRAWINGS

[0062] 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.

[0063] Figs, la and lb show a LED filament lamp and a LED filament, respectively, according to the prior art,

[0064] Fig. 2 schematically shows a LED filament arrangement according to an exemplifying embodiment of the present invention,

[0065] Fig. 3 schematically shows operations of a LED filament arrangement according to an exemplifying embodiment of the present invention, 2024PF80122

[0066] 12

[0067] Figs. 4a-d, 5 and 6 schematically show LED filament arrangements according to exemplifying embodiments of the present invention, and

[0068] Fig. 7 schematically shows a lamp comprising a LED filament arrangement according to an exemplifying embodiment of the present invention.

[0069] DETAILED DESCRIPTION

[0070] Fig. la 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.

[0071] In particular, spiral-shaped red-green-blue-white (RGBW) LED filaments have become the dominant LED filament architecture for LED filaments providing white and colored light, and an example of such LED filaments 30 is shown in Fig. lb. However, customer feedback has indicated that these types of RGBW LED filaments 30 of the prior art often suffer from a deteriorated aesthetical appearance, and in particular that these LED filaments 30 are too wide. It should be noted that attempts (only) focused on augmenting this aesthetical aspect may lead to a risk that the efficiency and / or luminous flux of the light emitted from these LED filament lamps becomes non-optimal. Hence, it is of interest to further improve the visual appearance of the LED filament lamps whilst ensuring the lightemitting properties of the light emitted from the LED filaments.

[0072] Fig. 2 shows a cross-sectional view of a LED filament arrangement 100 according to an exemplifying embodiment of the present invention. The LED filament arrangement 100 is configured to emit LED filament arrangement light 105, schematically indicated in an upwards and downwards direction with respect to the view of the LED filament arrangement 100 of Fig. 2. The LED filament arrangement 100 comprises a first LED filament 110a and a second LED filament 110b. The first LED filament 110a, which is configured to emit first LED filament light 115a, comprises a first elongated carrier 120a. A plurality of first LEDs 130a is arranged on a first major surface 140a of the first elongated carrier 120a. It should be noted that the first LED filament 110a may comprise substantially any number of array(s) of the plurality of first LEDs 130a. The plurality of first LEDs 130a preferably comprises more than 5 LEDs, more preferably more than 8 LEDs, and even more 2024PF80122

[0073] 13 preferred more than 10 LEDs. The plurality of first LEDs 130a may be direct emitting LEDs. The plurality of first LEDs 130a is configured to emit first LED light 150a having a first peak emission wavelength, I, in a first blue wavelength range of 430 - 500 nm. For example, one preferred sub range of the first blue wavelength range is 440 - 460 nm. Another preferred sub range of the first blue wavelength range is 480 - 500 nm. The first LED filament 110a further comprises a first encapsulant 160a covering the plurality of first LEDs 130a and at least part of the first major surface 140a of the first elongated carrier 120a. The LED filament arrangement 100 further comprises a second LED filament 110b configured to emit second LED filament light 115b. The second LED filament 110b comprises a second elongated carrier 120b and a plurality of second LEDs 130b arranged on a first major surface 140b of the second elongated carrier 120b. It should be noted that the second LED filament 110b may comprise substantially any number of array(s) of the plurality of second LEDs 130b. The plurality of second LEDs 130b preferably comprises more than 5 LEDs, more preferably more than 8 LEDs, and even more preferred more than 10 LEDs. The plurality of second LEDs 130b may be direct emitting LEDs. The plurality of second LEDs 130b is configured to emit second LED light 150b having a second peak emission wavelength, X2, in a second blue wavelength range of 400 - 490 nm. The second LED filament 110b further comprises a plurality of third LEDs 130c arranged on the first major surface 140a of the second elongated carrier 120b. It should be noted that the second LED filament 110b may comprise substantially any number of array(s) of the plurality of third LEDs 130c. The plurality of third LEDs 130c preferably comprises more than 5 LEDs, more preferably more than 8 LEDs, and even more preferred more than 10 LEDs. The plurality of third LEDs 130c may be direct emitting LEDs. The plurality of third LEDs 130c is configured to emit third LED light 150c having a third peak emission wavelength, X3, in a green wavelength range of 500 - 540 nm, such as e.g. 510 - 540 nm. In Fig. 2, the plurality of second LEDs 130b and the plurality of third LEDs 130c are respectively arranged in arrays, which are aligned in parallel and adjacent to each other. The second LED filament 110b further comprises a second encapsulant 160b covering the plurality of second LEDs 130b and the plurality of third LEDs 130c. The second encapsulant 160b covers at least part of the first major surface 140b of the second elongated carrier 120b. The second encapsulant 160b comprises luminescent material configured to at least partly convert the emitted second LED light 150b into converted light 170 having a fourth peak emission wavelength, X4, in a red wavelength range of 600 - 675 nm. The luminescent material of the second encapsulant 160b may comprise a first red 2024PF80122

[0074] 14 phosphor of the type M’xM2-2xAX6 doped with tetravalent manganese, wherein M’ comprises an alkaline earth cation, M comprises an alkaline cation, and x is selected from the range of 0 - 1, wherein A comprises a tetraval ent cation, wherein X comprises a monovalent anion, at least comprising fluorine. For example, at least 80% of the luminescent material in the second encapsulant 160b may be the first red phosphor. Although not shown, the thickness of the first encapsulant 160a and / or the second encapsulant 160b may vary over the length of the first and second LED filaments 110a, 110b, respectively. The concentration of the luminescent material in the second encapsulant 160b may be in a range of 3 - 15 v / v%. Furthermore, the concentration of the luminescent material in the second encapsulant 160b may vary over the length of the second LED filament 110b.

[0075] According to the example of the LED filament arrangement 100 in Fig. 2, the first elongated carrier 120a and the second elongated carriers 120b are light-transmissive e.g. translucent such as light diffusive or transparent. Furthermore, the first encapsulant 160a at least partially covers a second major surface 400a, opposite the first major surface 140a, of the first elongated carrier 120a, and the second encapsulant 160b at least partially covers a second major surface 400b, opposite the first major surface 140b, of the second elongated carrier 120b.

[0076] The LED filament arrangement 100 in Fig. 2 further comprises a schematically indicated controller 200 which is connected to the first LED filament 110a and the second LED filament 110b. It will be appreciated that the controller 200 may be connected to the plurality of first LEDs 130a, the plurality of second LEDs 130b, and the plurality of third LEDs 130c via wire or wirelessly. Furthermore, the position of the controller 200 is schematically indicated in Fig. 2, as the controller 200 may be arranged adjacent (in a vicinity of) the first and second LED filaments 110a, 110b or at a distance from these. The controller 200 is configured to individually control emission of the first LED light 150a, the second LED light 150b, and the third LED light 150c.

[0077] Fig. 3 schematically shows operations of a LED filament arrangement 100 according to an exemplifying embodiment of the present invention. More specifically, Fig. 3 schematically shows an operation of the controller 200 of the LED filament arrangement 100 as exemplified in Fig. 2, and it is further referred to Fig. 2 for an increased understanding of the functions and / or features of the LED filament arrangement 100 and / or the controller 200. According to Fig. 3, the controller 200 may be configured to operate in (i) a first operational mode 300a, (ii) a second operational mode 300b, (iii) a third operational mode 300c, and / or 2024PF80122

[0078] 15

[0079] (iv) a fourth operational mode 300d. The (i) first operational mode 300a comprises emission of the first LED light 150a, non-emission of the second LED light 150b, and non-emission of the third LED light 150c, whereby the emitted LED filament arrangement light 105 is blue light 310a. The (ii) second operational mode 300b comprises non-emission of the first LED light 150a, non-emission of the second LED light 150b, and emission of the third LED light 150c, whereby the emitted LED filament arrangement light 105 is green light 310b. The (iii) third operational mode 300c comprises non-emission of the first LED light 150a, emission of the second LED light 150b, and non-emission of the third LED light 150c, whereby the emitted LED filament arrangement light 105 is red light 310c. The (iv) fourth operational mode 300d comprises emission of the first LED light 150a, emission of the second LED light 150b, and emission of the third LED light 150c. The emitted LED filament arrangement light 105 is white light 3 lOd having a correlated color temperature, CCT, in a range of 1500 - 6500 K and a color rendering index, CRI, of at least 80.

[0080] Figs. 4a-d schematically show LED filament arrangements 100 according to exemplifying embodiments of the present invention. It will be appreciated that the LED filament arrangements 100 shown in Figs. 4a-d correspond to the LED filament arrangement 100 Fig. 2, and that it is referred to Fig. 2 for an increased understanding of the features and functions of the LED filament arrangements 100 shown in Figs. 4a-d.

[0081] Fig. 4a shows an exemplifying embodiment of the LED filament arrangement 100, wherein the first LED filament 110a and the second LED filament 110b are arranged in parallel, and wherein a first normal, Ni, of the first major surface 140a of the first elongated carrier 120a and a second normal, N2, of the first major surface 140b of the second elongated carrier 120b are parallel to each other. Furthermore, in the LED filament arrangement 100 according to Fig. 4a, the first LED filament 110a and the second LED filament 110b are arranged in abutment with each other.

[0082] Fig. 4b shows an exemplifying embodiment of the LED filament arrangement 100, wherein the first LED filament 110a and the second LED filament 110b are arranged in parallel, and wherein a first normal, Ni, of the first major surface 140a of the first elongated carrier 120a and a second normal, N2, of the first major surface 140b of the second elongated carrier 120b are arranged with an angle, a, between the first normal, Ni, and the second normal, N2, wherein the angle, a, is in a range of 20° - 70°, such as in a range of 35° - 55°. Furthermore, in the LED filament arrangement 100 according to Fig. 4b, the first LED filament 110a and the second LED filament 110b are arranged in abutment with each other. 2024PF80122

[0083] 16

[0084] Fig. 4c shows an exemplifying embodiment of the LED filament arrangement 100 according to Fig. 3a, i.e. wherein the first and second normals, Ni, N2, are parallel to each other. Furthermore, in the LED filament arrangement 100 according to Fig. 3c, the first LED filament 110a and the second LED filament 110b are arranged at a distance, d, from each other.

[0085] Fig. 4d shows an exemplifying embodiment of the LED filament arrangement 100 according to Fig. 3b, i.e. wherein the first and second normals, Ni, N2, are arranged with an angle, a, therebetween, wherein the angle, a, is in a range of 20° - 70°, such as in a range of 35° - 55°. Furthermore, in the LED filament arrangement 100 according to Fig. 3d, the first LED filament 110a and the second LED filament 110b are arranged at a distance, d, from each other.

[0086] Fig. 5 shows an exemplifying embodiment of the LED filament arrangement 100. The configuration of the LED filament arrangement 100 is similar to Fig. 4c, in that the first and second normals, Ni, N2, are parallel to each other, and that the first LED filament 110a and the second LED filament 110b are arranged at a distance, d, from each other. Furthermore, a (schematically indicated) reflector 450 is arranged between the first LED filament 110a and the second LED filament 110b.

[0087] Fig. 6 shows an exemplifying embodiment of the LED filament arrangement 100, wherein the first LED filament 110a and the second LED filament 110b are arranged in a spiral shape. It will be appreciated that the spiral defined by the first and second LED filaments 110a, 110b may have a uniform diameter along its axis, as shown in Fig. 6, or that it alternatively may have an increasing and / or decreasing diameter along its axis.

[0088] Fig. 7 schematically shows a lamp 500 according to an embodiment of the present invention. The lamp 500, which may constitute a lamp or a luminaire, comprises a LED filament arrangement 100 according to any one of the previously described embodiments. The lamp 500 further comprises a cover 505, which is exemplified as being bulb-shaped. The cover 505 may comprise an at least partially light transmissive (e.g. transparent) material and at least partially encloses the LED filament arrangement 100. The lamp 500 further comprises an electrical connection 510 connected to the LED filament arrangement 100 for a supply of power to the plurality of LED filaments of the LED filament arrangement 100. The controller 200 of the LED filament arrangement 100 is exemplified as being integrated in the electrical connection 510. 2024PF80122

[0089] 17

[0090] 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 both of the first and second LED filaments 110a, 110b, the spiral of the first and second LED filaments 110a, 110b, etc., may have different shapes, dimensions and / or sizes than those depicted / described.

Claims

2024PF8012218CLAIMS:

1. A light emitting diode, LED, filament arrangement (100), configured to emitLED filament arrangement light (105), comprising: a first LED filament (110a) configured to emit first LED filament light (115a) and comprising:- a first elongated carrier (120a),- a plurality of first LEDs (130a) arranged on a first major surface (140a) of the first elongated carrier, wherein the plurality of first LEDs is configured to emit first LED light (150a) having a first peak emission wavelength, I, in a first blue wavelength range of 430 - 500 nm, and- a first encapsulant (160a) covering the plurality of first LEDs and at least part of the first major surface of the first elongated carrier, a second LED filament (110b) configured to emit second LED filament light (115b) and comprising:- a second elongated carrier (120b),- a plurality of second LEDs (130b) arranged on a first major surface (140b) of the second elongated carrier, wherein the plurality of second LEDs is configured to emit second LED light (150b) having a second peak emission wavelength, X2, in a second blue wavelength range of 400 - 490 nm,- a plurality of third LEDs (130c) arranged on the first major surface of the second elongated carrier, wherein the plurality of third LEDs is configured to emit third LED light (150c) having a third peak emission wavelength, X3, in a green wavelength range of 500 - 540 nm, and- a second encapsulant (160b) covering the plurality of second LEDs and the plurality of third LEDs and covering at least part of the first major surface of the second elongated carrier, wherein the second encapsulant comprises a luminescent material configured to at least partly convert the emitted second LED light into converted light (170) having a fourth peak emission wavelength, X4, in a red wavelength range of 600 - 675 nm, and2024PF8012219 a controller (200) connected to the plurality of first LEDs, the plurality of second LEDs and the plurality of third LEDs, wherein the controller is configured to individually control emission of the first LED light, the second LED light, and the third LED light, and wherein the controller is configured to operate in(i) a first operational mode (300a), comprising: emission of the first LED light, non-emission of the second LED light, and non-emission of the third LED light, whereby the emitted LED filament arrangement light is blue light (310a),(ii) a second operational mode (300b), comprising non-emission of the first LED light, non-emission of the second LED light, and emission of the third LED light, whereby the emitted LED filament arrangement light is green light (310b),(iii) a third operational mode (300c), comprising non-emission of the first LED light, emission of the second LED light, and non-emission of the third LED light, whereby the emitted LED filament arrangement light is red light (310c), and(iv) a fourth operational mode (300d), comprising emission of the first LED light, emission of the second LED light, and emission of the third LED light, whereby the emitted LED filament arrangement light is white light (3 lOd) having a correlated color temperature, CCT, in a range of 1500 - 6500 K and a color rendering index, CRI, of at least 80.

2. The LED filament arrangement according to claim 1, wherein the luminescent material of the second encapsulant comprises a first red phosphor of the type M’xM2-2xAX62024PF8012220 doped with tetravalent manganese, wherein M’ comprises an alkaline earth cation, M comprises an alkaline cation, and x is selected from the range of 0 - 1, wherein A comprises a tetravalent cation, wherein X comprises a monovalent anion, at least comprising fluorine.

3. The LED filament arrangement according to claim 2, wherein at least 80% of the luminescent material in the second encapsulant is the first red phosphor.

4. The LED filament arrangement according to any one of the preceding claims, wherein the first elongated carrier and the second elongated carrier are light-transmissive, the first encapsulant at least partially covers a second major surface (400a), opposite the first major surface, of the first elongated carrier, and the second encapsulant at least partially covers a second major surface (400b), opposite the first major surface, of the second elongated carrier.

5. The LED filament arrangement according to any one of the preceding claims, wherein the first LED filament and the second LED filament are arranged in parallel, and wherein a first normal, Ni, of the first major surface of the first elongated carrier and a second normal, N2, of the first major surface of second elongated carrier, are, one of parallel to each other, and arranged with an angle, a, between the first normal, Ni, and the second normal, N2, wherein the angle, a, is in a range of 20° - 70°.

6. The LED filament arrangement according to claim 5, wherein the first LED filament and the second LED filament are arranged in abutment with each other.

7. The LED filament arrangement according to claim 5, wherein the first LED filament and the second LED filament are arranged at a distance, d, from each other.

8. The LED filament according to claim 7, wherein a reflector (450) is arranged between the first LED filament and the second LED filament.

9. The LED filament arrangement according to any one of the preceding claims, wherein the first LED filament and the second LED filament are arranged in a spiral shape.2024PF801222110. The LED filament arrangement according to any one of the preceding claims, wherein the second blue wavelength range is 420 - 475 nm, the first blue wavelength range is 480 - 500 nm, and the green wavelength range is 510 - 540 nm.

11. The LED filament arrangement according to any one of the preceding claims, wherein the luminescent material of the second encapsulant comprises a second red phosphor, wherein the second red phosphor comprises at least one of a nitride phosphor and an oxynitride phosphor.

12. The LED filament arrangement according to any one of the preceding claims, wherein the concentration of the luminescent material in the second encapsulant is in a range of 3 - 15 v / v%.

13. A lamp (500), comprising: the LED filament arrangement according to any one of the preceding claims, a cover (505) comprising an at least partially transparent material, wherein the cover at least partially encloses the LED filament arrangement, and a connector (510) electrically connected to the LED filament arrangement for a supply of power to the plurality of first LEDs, the plurality of second LEDs, and the plurality of third LEDs.

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