LED filament arrangement

Abstract

A light emitting diode, LED, filament arrangement comprising a LED filament and a controller. The LED filament comprises an elongated carrier, a first one-dimensional array of a plurality of first LEDs and a second one-dimensional array of a plurality of second LEDs are arranged along the elongation direction on the elongated carrier. The LED filament comprises a luminescent elongated encapsulant comprising a luminescent material at least partly enclosing the first one-dimensional array. The first one-dimensional array comprises a plurality of red LEDs and a plurality of first blue LEDs. The second one-dimensional array comprises a plurality of green LEDs and a plurality of second blue LEDs. The luminescent material comprises a green-yellow phosphor configured to at least partially convert first blue LED light emitted by the first blue LEDs into green-yellow converted light.

Description

[0001] LED filament arrangement

[0002] FIELD OF THE INVENTION

[0003] The present invention generally relates to light emitting devices. More specifically, the present invention is related to a light emitting diode (LED) filament arrangement comprising a LED filament and a controller.

[0004] BACKGROUND OF THE INVENTION

[0005] The original bulb lamps powered by electricity were of the type having metal wire filaments enclosed within more or less evacuated glass bulbs. This type of bulb lamps was the ubiquitous choice of light source for more than a century until the introduction of LEDs. Light sources based on LEDs have now replaced the light bulb as a source of light in homes and in many other locations. Initially, mainly due to the inherent structural characteristics of LEDs, the early LED light sources (i.e. LED lamps) did not resemble the earlier light bulbs and in many cases were considered as aesthetically inferior to a light bulb of the earlier type. Thus, for aesthetic reasons, a desire for light sources having the look of the traditional bulb shaped filament lamp came back when it was found that this was technically feasible to make light sources using LED filaments.

[0006] However, there still remain various aspects of such light sources using LED filaments. For example, there is still a need for improving the performance and / or the appearance of light sources using LED filaments. There exist red-green-blue-white (RGBW) LED filaments. Market research shows that the width of current RGBW LED filaments is too large from an aesthetical point of view.

[0007] SUMMARY OF THE INVENTION

[0008] It is of interest to provide a LED filament arrangement that is capable of overcoming drawbacks of prior art devices.

[0009] This and other objects are achieved in a first aspect by providing a LED filament arrangement having the features of the appended independent claim. Preferred embodiments are defined in the appended dependent claims. Hence, according to the present invention there is provided a light emitting diode, LED, filament arrangement. The LED filament arrangement comprises a LED filament and a controller. The LED filament is configured to provide, in operation, LED filament light. The LED filament comprises an elongated carrier having an elongation direction .

[0010] The LED filament may comprise two separate sub-filaments. The elongated carrier may comprise two elongated sub-carriers. Each of the two sub-carriers may comprise one of the two sub-filaments. The LED filament may comprise a plurality of separate subfilaments and a plurality of sub-carriers. Each of the plurality of sub-carriers may comprise one of the plurality of sub-filaments. In other words, the LED filament may comprise or be in the form of a plurality of, e.g. a first and a second, elongated sub-filaments. Preferably, such sub-filaments are arranged parallel with each other and at a small distance, e.g. 2 mm, from each other such that the sub-filaments can be considered as a single LED filament.

[0011] A first one-dimensional array of a plurality of first LEDs and a second onedimensional array of a plurality of second LEDs are arranged along the elongation direction on the elongated carrier. The first one-dimensional array and the second one-dimensional array may be located on different sub-filaments. The LED filament may comprise a plurality of arrays of a plurality of LEDs. The plurality of arrays may be located on the plurality of sub-filaments.

[0012] The word LED should be interpreted that it can be one single LED (light source) or it can be some LEDs or a cluster of LEDs of the same color.

[0013] The fact that the arrays are one-dimensional arrays implies that the driver is arranged to drive both the first LEDs and the second LEDs according to the linear configuration of the first LEDs and the second LEDs.

[0014] The LED filament comprises a luminescent elongated encapsulant. A luminescent elongated encapsulant comprising a luminescent material is arranged along the elongation direction of the elongated carrier. The luminescent elongated encapsulant at least partly enclosing the plurality of red LEDs (112) and at least partly enclosing the plurality of first blue LEDs. The luminescent elongated encapsulant may fully enclose the first onedimensional array of the plurality of first LEDs. The luminescent elongated encapsulant may not enclose or cover the second one-dimensional array of the plurality of second LEDs.

[0015] The first one-dimensional array of the plurality of first LEDs comprises i: a plurality of red LEDs configured to emit, in operation, red LED light; ii: a plurality of first blue LEDs configured to emit, in operation, first blue LED light. The second one- dimensional array of the plurality of second LEDs comprises iii: a plurality of green LEDs configured to emit, in operation, green LED light; iv: a plurality of second blue LEDs configured to emit, in operation, second blue LED light.

[0016] The luminescent material comprises a green-yellow phosphor. The greenyellow phosphor is configured to at least partially convert the first blue LED light emitted by the first blue LEDs into green-yellow converted light. The green-yellow phosphor may comprise a garnet phosphor such as YAG and / or LuAG phosphors.

[0017] The controller is configured to individually control: i emission of the red LED light emitted from said plurality of red LEDs; ii emission of first blue LED light emitted from said plurality of first blue LEDs; iii emission of green LED light emitted from said plurality of green LEDs; iv emission of second blue LED light emitted from said plurality of second blue LEDs.

[0018] Such a LED filament arrangement allows for emission of all colors and white. White light can be generated for example by the plurality of first blue LEDs interacting with the luminescent material, possibly with contribution from the plurality of red LEDs. By alternating two LED light colors in each respective array of LEDs, a slim configuration is achieved as compared to having separate arrays of LEDs for each LED color (red, green, blue and white). Thus, the LED filament arrangement disclosed enables RGBW LED filament with a smaller width than prior RGBW LED filaments. The two LED light colors in each array are further chosen to have a small difference in emission peak wavelength in order to prevent spottiness in the LED filament light. Spottiness may be defined as local peaks in the luminance level of light that can be precepted by a human eye. In other words, higher spottiness means that individual LEDs are increasingly visible.

[0019] In various embodiments, the LED filament may further comprise a transparent elongated encapsulant. The transparent elongated encapsulant may be arranged along the elongation direction of the elongated carrier. The transparent elongated encapsulant may at least partly enclose the second one-dimensional array of the plurality of second LEDs. The transparent elongated encapsulant may fully enclose the second one-dimensional array of the plurality of second LEDs. The LED filament may comprise a plurality of transparent elongated encapsulant, at least partly enclosing any array of a plurality of LEDs. An advantage of such a transparent elongated encapsulant is that the light emitted by the green LEDs and by the second blue LEDs is directed less towards the luminescent elongated encapsulant, thus reducing cross-talk. By cross-talk is meant that the luminescent material in the luminescent elongated encapsulant is excited by the green light of the green LEDs and / or by the second blue LED light of the second blue LEDs. In an embodiment, an elongated reflector may be arranged between the luminescent elongated encapsulant and the transparent elongated encapsulant.

[0020] In various embodiments, the controller may be configured to i: in a first operational mode, power the plurality of second blue LEDs such that the LED filament light is blue LED filament light; ii: in a second operational mode, power the plurality of green LEDs such that the LED filament light is green LED filament light; iii: in a third operational mode, power the plurality of red LEDs such that the LED filament light is red LED filament light; iv: in a fourth operational mode, power the plurality of first blue LEDs and optionally the plurality of red LEDs such that the LED filament light comprises the green-yellow converted light and the LED filament light is white LED filament light. In other words, the controller may be configured to: in the first, i, operational mode power only the plurality of second blue LEDs; in the second, ii, operational mode power only the plurality of green LEDs; in the third, iii, operational mode power only the plurality of red LEDs; in the fourth, iv, fourth operational mode, power only the plurality of first blue LEDs. The white LED filament light may have a first correlated color temperature (CCT1) in a range from 1500K to 6500K. The white LED filament light may have a first color rendering index, CRI, of at least 70 or of at least 80 or at least 85.

[0021] In other words, the color and the color temperature of the LED filament light is tunable, enabling a further improved appearance in that any desired color and color temperature may be achieved. In some embodiments, CCT1 may be in a range of 1700 K to 2500 K and preferably having a CRI of at least 70 or of at least 80. This later range of CCT further reduces cross-talk of the white LED light with the green LEDs and second blue LED light, especially if the luminescent material further comprise a first red phosphor as defined below.

[0022] In various embodiments, the luminescent material may further comprise a first red phosphor. The first red phosphor may be configured to at least partially convert the first blue LED light and / or the green-yellow converted light into first red converted light. The first red phosphor may comprise a phosphor of the type M’xM2-2xAX6. M’ may comprise an alkaline earth cation. M may comprises an alkaline cation, x is in the range of 0-1. A may comprise a tetravalent cation. For example, A may comprise one or more of silicon and titanium. X may comprise a monovalent anion. X may comprise fluorine (F), for example Potassium Fluorosilicate, PFS, or potassium hexafluoromanganate, KSiF e.g. K2SiF6:Mn4+ Phosphor. The first red phosphor may be doped with tetravalent manganese. A phosphor of the type M’xM2-2xAX6 is advantageous because it hardly absorbs (and converts) long- wavelength blue light (480 nm - 500 nm) and does not absorb (e.g. <1% or 0%) green light (e.g. 500 nm - 530 nm). This is in contradiction to other red phosphors which absorb (and converts) long-wavelength blue light and green light well. A phosphor of the type M’XM2- 2XAXe absorbs short-wavelength blue light (430 to 480 nm, preferably in a range from 440 to 465 nm) well.

[0023] At least one source of red light is required in order to make the white LED filament light. The first red converted light is one such source. The red converted light may improve the light quality of the LED filament light. An advantage of the first red phosphor is that it can not be excited by green light and it is barely excited by long-wavelength blue light, thus preventing cross-talk with the luminescent elongated encapsulant. In embodiments, in the fourth operational mode, the LED filament light may comprise the green-yellow converted light and the red converted light (and part of the first blue LED light). The LED filament light may be white LED filament light having a first correlated color temperature, CCT1, in a range from 1500K to 6500K (espcially in a range from 1700 K to 3000K) and optionally a first color rendering index, CRI, of at least 80. LED filament light having a lower CCT and comprising red converted light means a relatively larger percentage of the phosphor in the luminescnet elongated encapsulant may be a phosphor of the type M’xNfc. 2xAXe thus reducing crosstalk.

[0024] The luminescent elongated encapsulant may be free from any red phosphor. If the luminescent elongated encapsulant is free from any red phosphor, the white LED filament light comprises the red LED light. In other words, in this case the plurality of red LEDs is the only source of red light used to make the white LED filament light.

[0025] The peak emission wavelength of the first blue LED light may be in a wavelength range from 420 to 500 nm, preferably in a wavelength range from 430 to 480 nm, more preferably in a wavelength range from 440 to 465 nm. Such a range of wavelengths assures optimal excitation of the phosphors and good quality blue light in the white light. The peak emission wavelength of the red LED light may be in a wavelength from 600 to 660 nm, preferably in a wavelength from 610 to 650 nm.

[0026] The peak emission wavelength of the second blue LED light may be in a wavelength range from 480 to 500 nm, preferably in a wavelength range from 485 to 500 nm, more preferably in a wavelength range from 485 to 495nm. The peak emission wavelength of the green LED light may be in a wavelength range from 500 to 530 nm preferably in a wavelength range from 505 to 530nm. Such a range of wavelengths reduces cross-talk with the luminescent elongated encapsulant, especially in combination with red phosphor as defined above.

[0027] The peak emission wavelength of the green-yellow converted light may be in a wavelength range from 500 to 590 nm or in a wavelength range from 540 to 590 nm.

[0028] The peak emission wavelength of the first red converted light may be in a wavelength range from 600 to 660 nm, preferably in a wavelength range from 620 nm to 640 nm. Said first red phosphor may be a narrow band phosphor having for example a full width at half maximum smaller than or equal to 40 nm.

[0029] The difference in the peak emission wavelength of the green LED light and the peak emission wavelength of the second blue LED light may be in a wavelength range from 20 to 40 nm. This ensures that when switching between the green LED light and the second blue LED light, or when using both the green LED light and the second blue LED light, the color contrast is reduced and spottiness of the LED filament light may be reduced.

[0030] The peak emission wavelength of the first red converted light may be shorter than the peak emission wavelength of the red LED light. The difference in the peak emission wavelength of the first red converted light and the peak emission wavelength of the red LED light may be in a wavelength range from 5 nm to 30 nm or in a wavelength from 10 nm to 30 nm. Such a range of wavelengths results in improved red color and a high efficiency.

[0031] In various embodiments, the controller is further configured, during the first operational mode of the controller, to power the green LEDs to emit green light at an intensity below 30% or below 20% of a maximum intensity of the second blue light. In various embodiments, the controller is further configured, during the second operational mode of the controller, to power the second blue LEDs to emit second blue light at an intensity below 30% or below 20% of a maximum intensity of the green light. In this way, the spottiness of the LED filament light may be further reduced.

[0032] In various embodiments, the red LEDs and the first blue LEDs of the first onedimensional array are periodically arranged. The periodic arrangement may be such that every second LED along the elongation direction is one of the red LEDs and every other second LED is one of the first blue LEDs. In other words, the first blue LEDs and the red LEDs are arranged alternatingly within the first one-dimensional array. In various embodiments the green LEDs and the second blue LEDs of the first one-dimensional array are periodically arranged. The periodic arrangement may be such that every second LED along the elongation direction is one of the green LEDs and every other second LED is one of the second blue LEDs. In other words, the second blue LEDs and the green LEDs are arranged altematingly within the first one-dimensional array. Such arrangement further reduces the spottiness of the LED filament light. Other arrangements for the LEDs in the first one-dimensional array may be for example red-red-blue, or blue-blue-red, or red-red-blue- blue for the first one-dimensional array. Other arrangements for the LEDs in the second onedimensional array may be for example green-green-blue, or green-blue-blue, or green-green- blue-blue.

[0033] In a further aspect, there is provided a lamp or a luminaire comprising a LED filament arrangement as summarized above. The lamp or the luminaire may further comprise a connector mechanically and electrically connected to a socket of the lamp or the luminaire. In embodiments, the lamp may comprise an envelope at least partly enclosing the LED filament.

[0034] Such a lamp or luminaire provides the effects and advantages as summarized above.

[0035] BRIEF DESCRIPTION OF THE DRAWINGS

[0036] 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 where:

[0037] Fig. la schematically illustrates a LED filament arrangement,

[0038] Fig. lb schematically illustrates a detail of the LED filament in figure la, Fig. 1c schematically illustrates a cross section view along A-A of the LED filament illustrated in figure lb,

[0039] Fig. Id schematically illustrates a cross section view along B-B of the LED filament illustrated in figure lb,

[0040] Fig. 2 schematically illustrates a lamp,

[0041] Fig. 3 schematically illustrates a luminaire.

[0042] DETAILED DESCRIPTION

[0043] As illustrated in figure la, an embodiment of a LED filament arrangement 1 comprises a LED filament 100 and a controller 101. The LED filament 100 is configured to provide, in operation, LED filament light 116, 118, 126, 128. The controller 101 may be connected to the LED filament 100 via any means of wired or wireless connection. The controller may receive input from a user interface, a sensor and / or a clock module. Figure lb illustrates an embodiment of a LED filament 100 comprising an elongated carrier 102 having an elongation direction 101.

[0044] The LED filament 100 may comprise two separate sub-filaments. The elongated carrier 102 may comprise two elongated sub-carriers. Each of the two sub-carriers may then comprise one each of these two sub-filaments. The LED filament 100 may comprise a plurality of separate sub-filaments and a plurality of sub-carriers, each of the plurality of sub-carriers may comprise one of the plurality of sub-filaments.

[0045] A first one-dimensional array 110 of a plurality of first LEDs 112, 114 and a second one-dimensional array 120 of a plurality of second LEDs 122, 124 are arranged along the elongation direction 101 on the elongated carrier 102.

[0046] In various embodiments, the first one-dimensional array 110 and the second one-dimensional array 120 may be located on different sub-filaments. In some embodiments, the LED filament may comprise a plurality of arrays of a plurality of LEDs and the plurality of arrays may be located on the plurality of sub-filaments.

[0047] A luminescent elongated encapsulant 104 comprising a luminescent material 130 is arranged along the elongation direction 101 of the elongated carrier 102. The luminescent elongated encapsulant 104 at least partly encloses the first one-dimensional array 110 of the plurality of first LEDs 112. For example, the luminescent elongated encapsulant 104 may fully enclose the first one-dimensional array 110 of the plurality of first LEDs 112. The luminescent elongated encapsulant 104 may not enclose or cover the second onedimensional array 120 of the plurality of second LEDs 122, 124.

[0048] The first one-dimensional array 110 of the plurality of first LEDs 112, 114 comprises a plurality of red LEDs 112 configured to emit, in operation, red LED light and a plurality of first blue LEDs 114 configured to emit, in operation, first blue LED light. The second one-dimensional array 120 of the plurality of second LEDs 122, 124 comprises a plurality of green LEDs 122 configured to emit, in operation, green LED light and a plurality of second blue LEDs 124 configured to emit, in operation, second blue LED light. In an embodiment, at least 90% of the plurality of first LEDs in the first one-dimensional array 110 are either red LEDs 112 or first blue LEDs 114. In an embodiment, at least 90% of the plurality of first LEDs are either red LEDs 112 or first blue LEDs 114. In an embodiment, at least 90% of the plurality of second LEDs in the second one-dimensional array 120 are either green LEDs 112 or second blue LEDs 114.

[0049] In various embodiments, the red LEDs 112 and the first blue LEDs 114 of the first one-dimensional array 110 may be periodically arranged. This periodic arrangement may be such that every second LED of the first one-dimensional array 110, along the elongation direction 101, is one of the red LEDs 112 and every second LED is one of the first blue LEDs 114. In the same manner the green LEDs 122 and the second blue LEDs 124 of the second one-dimensional array 120 may be periodically arranged. This periodic arrangement may be such that every second LED of the second one-dimensional array 120, along the elongation direction 101, is one of the green LEDs 122 and every second LED is one of the second blue LEDs 124.

[0050] The luminescent material 130 of the luminescent elongated encapsulant 104 comprises a green-yellow phosphor. The green-yellow phosphor is configured to at least partially convert the first blue LED light emitted by the first blue LEDs 114 into greenyellow converted light 118.

[0051] In various embodiments, the LED filament 100 may further comprise a transparent elongated encapsulant 106 comprising a transparent material 132 arranged along the elongation direction 101 of the elongated carrier 102. The transparent material may comprise a crosslinked silicone such as crosslinked polydimethylsiloxane (PDMS), polydiphenylsiloxane (PDPS) and / or polymethylphenylsiloxane (PMPS). The transparent elongated encapsulant 106 may at least partly enclose the second one-dimensional array 120 of the plurality of second LEDs. The transparent elongated encapsulant 106 may fully enclose the second one-dimensional array 120 of the plurality of second LEDs. The LED filament 100 may comprise a plurality of transparent elongated encapsulant 106, at least partly enclosing an array of a plurality of LEDs.

[0052] The controller 101 is configured to individually control at least the following: i emission of the red LED light emitted from said plurality of red LEDs 112; ii emission of first blue LED light emitted from said plurality of first blue LEDs 114; iii emission of green LED light emitted from said plurality of green LEDs 122; iv emission of second blue LED light emitted from said plurality of second blue LEDs 124.

[0053] In various embodiments, the controller 101 may be configured to:

[0054] In a first operational mode, power the plurality of second blue LEDs 124 such that the LED filament light is blue LED filament light.

[0055] In a second operational mode, power the plurality of green LEDs 122 such that the LED filament light is green LED filament light.

[0056] In a third operational mode, power the plurality of red LEDs 112 such that the LED filament light is red LED filament light. In a fourth operational mode, power the plurality of first blue LEDs 114 and optionally the plurality of red LEDs 112 such that the LED filament light comprises the green-yellow converted light 118 and the LED filament light is white LED filament light.

[0057] In other words, the controller 101 may be configured to: in the first operational mode power only the plurality of second blue LEDs; in the second operational mode power only the plurality of green LEDs 122; in the third operational mode power only the plurality of red LEDs 112; in the fourth fourth operational mode, power only the plurality of first blue LEDs 114.

[0058] The white LED filament light may have a first correlated color temperature (CCT1) in a range from 1500K to 6500K. and may have a first color rendering index, CRI, of at least 70 or at least 80 or at least 85 e.g. CRI 86.

[0059] In other words, the color and the color temperature of the LED filament light is tunable, enabling a further improved appearance in that any desired color and color temperature may be achieved.

[0060] In some embodiments, CCT1 may be in a range of 1700 K to 2500 K and preferably having a CRI of at least 70 or of at least 80 or at least 85 e.g. 86. Such a range of CCT further reduces cross-talk of the white LED light with the green LEDs and second blue LED light, especially if the luminescent material further comprise a first red phosphor as defined below.

[0061] In various embodiments, the luminescent material 130 may further comprise a first red phosphor. The first red phosphor may be configured to at least partially convert the first blue LED light and / or the green-yellow converted light into first red converted light. The first red phosphor may comprise a phosphor of the type M’xM2-2xAX6 doped with tetravalent manganese. M’ may comprise an alkaline earth cation. M may comprises an alkaline cation, x is in the range of 0-1. A may comprise a tetravalent cation. For example, A may comprise one or more of silicon and titanium. X may comprise a monovalent anion. X may comprise fluorine (F), for example Potassium Fluorosilicate, PFS, or potassium hexafluoromanganate, KSiF e.g. K2SiF6:Mn4+ Phosphor. In some embodiments, the luminescent material 130 of the luminescent elongated encapsulant 104 is free from any red phosphor and the white LED filament light comprises the red LED light.

[0062] The peak emission wavelength of the first blue LED light may be in a wavelength range from 420 to 500 nm, preferably in a wavelength range from 430 to 480 nm, more preferably in a wavelength range from 440 to 465 nm. The peak emission wavelength of the red LED light may be in a wavelength from 600 to 660 nm, preferably in a wavelength from 610 to 650 nm.

[0063] The peak emission wavelength of the second blue LED light may be in a wavelength range from 485 to 500 nm, preferably in a wavelength range from 485 to 495nm. The peak emission wavelength of the green LED light may be in a wavelength range from 500 to 530 nm, preferably in a range from 505 to 530 nm.

[0064] The peak emission wavelength of the green-yellow converted light may be in a wavelength range from 500 to 590 nm.

[0065] The peak emission wavelength of the first red converted light may be in a wavelength range from 600 to 660 nm, preferably in a wavelength range from 620 nm to 640 nm. Said first red phosphor may be a narrow band phosphor having for example a full width at half maximum smaller than or equal to 40 nm.

[0066] The difference in the peak emission wavelength of the green LED light and the peak emission wavelength of the second blue LED light may be in a range from 20 to 40 nm.

[0067] The peak emission wavelength of the first red converted light may be shorter than the peak emission wavelength of the red LED light. The difference in the peak emission wavelength of the first red converted light and the peak emission wavelength of the red LED light may be between 5 nm and 30 nm.

[0068] In various embodiments, the controller 101 is further configured, during the first operational mode of the controller 101, to power the green LEDs 122 to emit green light at an intensity below 30% or below 20% of a maximum intensity of the second blue light. In various embodiments, the controller 101 is further configured, during the second operational mode of the controller 101, to power the second blue LEDs 124 to emit second blue light at an intensity below 30% or below 20% of a maximum intensity of the green light.

[0069] Fig. 2 shows an example of a further embodiment of a lamp 200 comprising a LED filament arrangement 1 as summarized above. The LED filament arrangement 1 may be at least partly enveloped by a lamp envelope 203. The lamp envelope may consist of glass or any other at least partially transparent material. The lamp 200 may further comprise a connector mechanically and electrically connected to a socket 201 of the lamp 200.

[0070] Fig. 3 shows an example of a further embodiment of a luminaire 300. The luminaire 300 may comprise a plurality of lamps 200 comprising LED filament arrangement 1 as summarized above. The luminaire 300 may further comprise a connector mechanically and electrically connected to a luminaire socket 301 of the luminaire 300.

Claims

CLAIMS:

1. A light emitting diode, LED, filament arrangement (1) comprising a LED filament (100) and a controller (101), the LED filament arrangement (1) being configured to provide, in operation, LED filament light, the LED filament (100) comprising: an elongated carrier (102) having an elongation direction (101); a first one-dimensional array (110) of a plurality of first light emitting diodes, LEDs (112, 114), arranged along the elongation direction (101) on the elongated carrier (102); a second one-dimensional array (120) of a plurality of second light emitting diodes, LEDs (122, 124), arranged along the elongation direction (101) on the elongated carrier (102); a luminescent elongated encapsulant (104) comprising a luminescent material (130), the luminescent elongated encapsulant (104) being arranged along the elongation direction (101) of the elongated carrier (102), wherein the first one-dimensional array (110) of the plurality of first LEDs (112, 114) consists of (i) a plurality of red LEDs (112) configured to emit, in operation, red LED light and (ii) a plurality of first blue LEDs (114) configured to emit, in operation, first blue LED light; wherein the luminescent elongated encapsulant (104) at least partly enclosing the plurality of red LEDs (112) and at least partly enclosing the plurality of first blue LEDs (H4); wherein the second one-dimensional array (120) of the plurality of second LEDs (122, 124) consists of (iii) a plurality of green LEDs (122) configured to emit, in operation, green LED light and (iv) a plurality of second blue LEDs (124) configured to emit, in operation, second blue LED light, wherein the luminescent material (130) comprises a green-yellow phosphor configured to at least partially convert the first blue LED light emitted by the first blue LEDs (114) into green-yellow converted light (118); wherein the red LEDs (112) and the first blue LEDs (114) of the first onedimensional array (110) are arranged alternatingly within the first one-dimensional array, andthe green LEDs (122) and the second blue LEDs (124) of the second one-dimensional array (110) are arranged alternatingly within the second one-dimensional array; and wherein the controller (101) is configured to individually control i: emission of the red LED light emitted from said plurality of red LEDs (112); ii: emission of first blue LED light emitted from said plurality of first blue LEDs (114); iii: emission of green LED light emitted from said plurality of green LEDs (122); and iv: emission of second blue LED light emitted from said plurality of second blue LEDs (124).

2. The LED filament arrangement (1) according to claim 1, wherein the controller (101) is configured to i: in a first operational mode, power the plurality of second blue LEDs (124) such that the LED filament light is blue LED filament light; ii: in a second operational mode, power the plurality of green LEDs (122) such that the LED filament light is green LED filament light; iii: in a third operational mode, power the plurality of red LEDs (112) such that the LED filament light is red LED filament light; iv: in a fourth operational mode, power the plurality of first blue LEDs (114) and optionally the plurality of red LEDs (112) such that the LED filament light comprises the green-yellow converted light (118) and the LED filament light is white LED filament light having a first correlated color temperature, CCT1, in a range from 1500K to 6500K and a first color rendering index, CRI, of at least 80.

3. The LED filament arrangement (1) according to claim 1 or claim 2, wherein the luminescent material (130) further comprises a first red phosphor configured to at least partially convert the first blue LED light and / or the green-yellow converted light into first red converted light.

4. The LED filament arrangement (1) according to claim 3, wherein the first red phosphor comprises a phosphor of the type M’xM2-2xAX6 doped with tetravalent manganese, wherein M’ comprises an alkaline earth cation, wherein M comprises an alkaline cation, and x is in the range of 0-1, wherein A comprises a tetravalent cation, for instance comprising one or more of silicon and titanium, and wherein X comprises a monovalent anion, at least comprising fluorine (F).

5. The LED filament arrangement (1) according to any one of the previous claims, wherein the peak emission wavelength of the first blue LED light is in a range from 430 to 480 nm, preferably in a range from 440 to 465 nm.

6. The LED filament arrangement (1) according to any one of the previous claims, wherein the peak emission wavelength of the second blue LED light is between 485 to 500 nm.

7. The LED filament arrangement (1) according to any one of the previous claims, wherein the peak emission wavelength of the green LED light is in a range from 500 to 530 nm.

8. The LED filament arrangement (1) according to any one of the previous claims, wherein the difference in the peak emission wavelength of the green LED light and the peak emission wavelength of the second blue LED light is in a range from 20 to 40 nm.

9. The LED filament arrangement (1) according to any one of the previous claims, wherein the LED filament light is white light having a correlated color temperature in a range from 1700 K to 2500 K, preferably having a Color Rendering Index, CRI, of at least 80.

10. The LED filament arrangement (1) according to any one of the previous claims, wherein the peak emission wavelength of the first red converted light is shorter than the peak emission wavelength of the red LED light.

11. The LED filament arrangement (1) according to any one of the claims 3-10, wherein the difference in the peak emission wavelength of the red LEDs (112) and the peak emission wavelength of the first red converted light is between 5 nm and 30 nm.

12. The LED filament arrangement (1) according to any one of the claims 2-11, wherein the luminescent material (130) of the luminescent elongated encapsulant (104) is free from any red phosphor, and wherein the white LED filament light comprises the red LED light.

13. The LED filament arrangement (1) according to any one of claims 2 to 12, wherein one or more of the following applies: during the first operational mode the controller (101) is further configured to power the green LEDs (122) to emit green light at an intensity below 30% of a maximum intensity of the second blue light; and during the second operational mode the controller (101) is further configured to power the second blue LEDs (124) to emit second blue light at an intensity below 30% of a maximum intensity of the green light.

14. A lamp (200) or a luminaire (300) comprising a LED filament arrangement (1) according to any one of the preceding claims.

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