A LED filament arrangement

Abstract

A light emitting diode, LED, filament arrangement (200) comprising a LED filament (1; 100) configured to, in operation, provide LED filament light (21, 22) and comprising: an elongated carrier (3) being light transmissive and comprising a first major surface (31) and a second major surface (32), a plurality of first LED light sources (4) configured to, in operation, emit first LED light source light (41) and being arranged on the first major surface (31), and a plurality of second LED light sources (5) configured to, in operation, emit second LED light source light (51) and being arranged on the first major surface (31), wherein the plurality of first LED light sources (4) is configured to emit, in operation, at least a part of the first LED light source light (41) in a first direction (D1) facing away from the first major surface (31), and the plurality of second LED light sources (5) is configured to emit, in operation, at least a part of the second LED light source light (51) in a second direction (D2) facing away from the second major surface (32), and wherein the LED filament light (21, 22) comprises first sub-LED filament light (21) emitted in a direction facing away from the first major surface (31) and second sub-LED filament (22) light emitted in a direction facing away from the second major surface (32).

Description

[0001] A LED filament arrangement

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a light emitting diode, LED, filament arrangement comprising a LED filament configured to, in operation, emit LED filament light. The invention further relates to a lamp and a luminaire comprising such a LED filament arrangement.

[0004] BACKGROUND OF THE INVENTION

[0005] LED filament technology is the dominant architecture in lamps. Next to lamps, a recent development is application of LED filaments in luminaires, but also in applications other than general illumination such as disinfection, horticulture and streetlighting.

[0006] A LED filament is providing LED filament light and comprises a plurality of light emitting diodes (LEDs) arranged in a linear array. Preferably, the LED filament has a length L and a width W, wherein L > 5W. The 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. Preferably, the LEDs are arranged on an elongated carrier like for instance a carrier, 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).

[0007] In case the elongated carrier comprises a first major surface and an opposite second major surface, the LEDs are arranged on at least one of these surfaces. The elongated carrier may be light transmissive, such as translucent and preferably transparent.

[0008] As used herein, the terms carrier and elongated carrier may be used interchangeably, such that the elongated carrier may also simply be denoted carrier.

[0009] The LED filament may comprise an encapsulant at least partly covering at least part of the plurality of LEDs. The encapsulant may also at least partly cover at least one of the first major surface and second major surface. The encapsulant may be a polymer material which may be flexible such as for example a silicone. Further, the LEDs may be arranged for emitting LED light, e.g., of different colors or spectrums. The encapsulant may comprise a luminescent material that is configured to convert at least a part of the first and / or second LED light source light into converted light. The luminescent material may be a phosphor such as an inorganic phosphor and / or quantum dots or rods (QDs). The term ‘luminescent material’ may also refer to a combination of two or more luminescent materials.

[0010] The LED filament may comprise multiple sub-filaments.

[0011] US 2020 / 0303354 Al discloses a LED-filament comprising a partially light- transmissive substrate, a plurality of blue LED chips mounted on a front face of the substrate, first broad-band green to red photoluminescence materials, and a first narrow-band manganese-activated fluoride red photoluminescence material covering the plurality of blue LED chips and the front face of the substrate, and second broad-band green to red photoluminescence materials covering the back face of the substrate.

[0012] It is desired to improve the optical performance and / or functionality of LED filaments, and especially to provide a LED filament having improved light distribution, and optionally beam-control.

[0013] WO 2020 / 190960 discloses an LED-filament that comprises: a light- transmissive substrate; a first array of LED chips on a front face of the substrate; a second array of LED chips on the front face of the substrate; a first photoluminescence arrangement covering the first array of LED chips; and a second photoluminescence arrangement covering the second array of LED chips; wherein the first array of LED chips and the first arrangement generate light of a first color temperature and the second array of LED chips and the second arrangement generate light of a second color temperature.

[0014] SUMMARY OF THE INVENTION

[0015] It is an object of the present invention to overcome this problem, and to provide a LED filament with an improved optical performance and / or functionality, and especially with an improved light distribution, and optionally also an improved beam-control.

[0016] According to a first aspect of the invention, this and other objects are achieved by means of a light emitting diode, LED, filament arrangement comprising a LED filament configured to, in operation, provide LED filament light, the LED filament comprising an elongated carrier being light transmissive and comprising a first major surface and a second major surface opposite to the first major surface, a plurality of first LED light sources configured to, in operation, emit first LED light source light and being arranged on the first major surface of the elongated carrier, and a plurality of second LED light sources configured to, in operation, emit second LED light source light and being arranged on the first major surface of the elongated carrier, wherein the plurality of first LED light sources is configured to emit, in operation, at least a part of the first LED light source light in a first direction, DI, facing away from the first major surface, and the plurality of second LED light sources is configured to emit, in operation, at least a part of the second LED light source light in a second direction, D2, opposite to the first direction, facing away from the second major surface, and wherein the LED filament light comprises first sub-LED filament light emitted in a direction facing away from the first major surface and second sub-LED filament light emitted in a direction facing away from the second major surface and at least partly passing through the elongated carrier.

[0017] Thereby, a LED filament arrangement with an improved optical performance and / or functionality, and especially with an improved light distribution, and optionally also an improved beam-control is provided.

[0018] The plurality of first LED light sources may be configured to emit, in operation, a majority of the first LED light source light in the first direction, DI, and the plurality of second LED light sources may be configured to emit, in operation, a majority of the second LED light source light in the second direction, D2.

[0019] Thereby, a LED filament arrangement with an improved optical performance, especially in terms of providing directional light, is provided, which is especially desired in such applications as disinfection and street lighting.

[0020] One or more of the following may apply: the first direction, DI, is facing away from and perpendicular to the first major surface, and the second direction, D2, is facing away from and perpendicular to the second major surface.

[0021] Thereby, a LED filament arrangement with a further improved optical performance, especially in terms of providing directional light, is provided.

[0022] The plurality of first LED light sources and the plurality of second LED light sources may be arranged in an alternating configuration.

[0023] Thereby, a LED filament arrangement comprising a slim design and a particularly improved color over angle performance is obtained.

[0024] Alternatively, the plurality of first LED light sources and the plurality of second LED light sources may be arranged parallel to each other.

[0025] The plurality of first LED light sources may comprise at least 10 LEDs or at least 20 LEDs.

[0026] The plurality of second LED light sources may comprise at least 10 LEDs or at least 20 LEDs.

[0027] The plurality of first LED light sources may comprise blue LEDs.

[0028] The plurality of second LED light sources may comprise blue LEDs. Thereby a LED filament arrangement with a particularly improved performance with respect to avoiding spottiness is obtained.

[0029] The elongated carrier may be transparent. Alternatively, or additionally, the elongated carrier may have a light transmissivity of at least 80 %.

[0030] Thereby a LED filament arrangement with a further improved optical performance is provided for due to reduced or even eliminated backscattering or absorption.

[0031] The LED filament arrangement may further comprise an elongated encapsulant at least partly enclosing the plurality of first LED light sources and the plurality of second LED light sources, the elongated encapsulant at least partly covering the first major surface, and the elongated encapsulant comprising one or more of a luminescent material and a light scattering material.

[0032] The light scattering material may be configured to scatter at least a part of the first and / or second LED light source light into scattered light.

[0033] Providing such an encapsulant provides for a LED filament arrangement with improved properties of the resulting LED filament light regarding at least one of homogeneity and adaptability in for instance color to various use situations.

[0034] The first sub-LED filament light may be white light having a first correlated color temperature, CCT, the second sub-LED filament light may be white light having a second CCT, and the second CCT may be different from the first CCT, for instance by at least 300K.

[0035] Thereby, a LED filament arrangement with which the resulting LED filament light may have different wavelength intervals or correlated color temperatures in the first and second direction, DI and D2, respectively, is provided.

[0036] The first sub-LED filament light may be white light having a first CCT, the second sub-LED filament light may be white light having a second CCT, and the second CCT may be different from the first CCT by 300 K or less.

[0037] Thereby, a LED filament arrangement with improved properties, particularly uniformity, of the resulting LED filament light regarding especially the wavelength interval or correlated color temperature is provided, which may be especially desired in such an application as horticulture.

[0038] The plurality of first LED light sources comprise a plurality of first LEDs, and the plurality of first LEDs may comprise top emitting LEDs.

[0039] Thereby, it may in a particularly simple manner be ensured that at least a part, or even a majority, of the first LED light source light is emitted in the first direction, DI. The plurality of second LED light sources comprise a plurality of second LEDs, and the plurality of second LEDs may comprise one or more of side emitting LEDs and bottom emitting LEDs.

[0040] Thereby, it may in a particularly simple manner be ensured that at least a part, or even a majority, of the second LED light source light is emitted in the second direction, D2.

[0041] The plurality of second LED light sources comprises a plurality of second LEDs, and the plurality of second LEDs may comprise top emitting LEDs, wherein the top emitting LEDs may be covered by a light reflective layer configured to redirect the second LED light in the second direction, D2.

[0042] Thereby a simpler and cheaper to manufacture LED filament arrangement is provided for since top emitting LED are standard, while simultaneously ensuring that at least a part, or even a majority, of the second LED light source light is emitted in the first direction, D2.

[0043] At least 65 % (or at least 75%) of the first LED light source light, which originates from the plurality of first LED light sources, may form the first sub-LED filament light, and / or at most 90 % (or at most 95%) of the first LED light source light, which originates from the plurality of first LED light sources, may form the first sub-LED filament light.

[0044] Thereby a LED filament arrangement with an improved efficiency is provided for.

[0045] At least 65 % (or at least 75%) of the second LED light source light, which originates from the plurality of second LED light sources, may form the second sub-LED filament light, and / or at most 90 % (or at most 95%) of the second LED light source light, which originates from the plurality of second LED light sources, may form the second sub- LED filament light.

[0046] Thereby a LED filament arrangement with an improved efficiency is provided for.

[0047] The elongated encapsulant may comprise a first part and a second part, the first part at least partly enclosing the plurality of first LED light sources and the plurality of second LED light sources, the first part of the elongated encapsulant at least partly covering the first major surface, and the second part at least partly covering the second major surface.

[0048] The first part and the second part may comprise the same optical properties. Alternatively, the first part and the second part may comprise mutually different optical properties. The term “optical properties” as used herein is intended to encompass at least such properties as light conversion, light scattering, light refraction, and light diffraction.

[0049] Thereby, a more versatile LED filament arrangement in terms of possible achievable light outputs is provided for.

[0050] The LED filament arrangement may be arranged to provide first sub-LED filament light having a first luminous flux (LF1) and second sub-LED filament light having a second luminous flux (LF2) wherein in an operational mode 0.9 < LF1 / LF2 < 1.1.

[0051] The LED filament arrangement may further comprise a controller configured to individually control the first LED light source light emitted by the plurality of first LED light sources and the second LED light source light emitted by the plurality of second LED light sources. In this way a luminous flux ratio between the first sub-LED filament light and the second sub-LED filament light is varied.

[0052] Thereby a LED filament arrangement with which the efficiency and the light quality, such as the color rendering index, CRI, of the resulting LED filament light may be adjusted is provided for.

[0053] The invention further relates to a LED filament lamp comprising a LED filament arrangement according to the invention.

[0054] The LED filament lamp may further comprise (i) a light transmissive envelope at least partly enclosing the LED filament arrangement and (ii) a base for electrically and mechanically connecting the LED filament lamp to a socket or a socket of a luminaire.

[0055] The invention further relates to a luminaire comprising a LED filament lamp according to the invention or comprising a LED filament arrangement according to the invention.

[0056] It is noted that the invention relates to all possible combinations of features recited in the claims.

[0057] BRIEF DESCRIPTION OF THE DRAWINGS

[0058] 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.

[0059] Fig. 1 shows a cross-sectional side view of a LED filament arrangement according to the invention and comprising a LED filament and a controller.

[0060] Fig. 2 shows a cross-sectional side view of the LED filament of the LED filament arrangement according to Fig. 1 seen along the line II-II in Fig. 1. Fig. 3 shows a cross-sectional side view of the LED filament of the LED filament arrangement according to Fig. 1 seen along the line III-III in Fig. 1.

[0061] Fig. 4 shows a cross-sectional side view of another LED filament arrangement according to the invention comprising another LED filament.

[0062] Fig. 5 shows a cross-sectional side view of the LED filament of the LED filament arrangement according to Fig. 4 seen along the line V-V in Fig. 4.

[0063] Fig. 6 shows a cross-sectional side view of the LED filament of the LED filament arrangement according to Fig. 4 seen along the line VI- VI in Fig. 4 and illustrating a different configuration as compared to Fig. 5.

[0064] Fig. 7 shows a cross-sectional side view of another LED filament of a LED filament arrangement according to the invention.

[0065] Fig. 8 shows a schematical side view of a lamp comprising a LED filament arrangement according to the invention.

[0066] Fig. 9 shows a schematical side view of a luminaire comprising a lamp and a LED filament arrangement according to the invention.

[0067] Figs. 10A-C show examples of top emitting LED light sources.

[0068] Figs. 11 A-C show examples of bottom emitting LED light sources.

[0069] As illustrated in the figures, the sizes of layers and regions are exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of embodiments of the present invention. Like reference numerals refer to like elements throughout.

[0070] DETAILED DESCRIPTION

[0071] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

[0072] Figs. 1-3 show cross-sectional side views of a light emitting diode, LED, filament arrangement 200 according to the invention and comprising a LED filament 1. More particularly, Fig. 1 shows a longitudinal cross-sectional view of the LED filament arrangement 200, while Figs. 2 and 3 show transversal cross-sectional side views of the LED filament 1 of the LED filament arrangement 200 as seen along the lines II-II and III-III, respectively, shown in Fig. 1.

[0073] Generally, and irrespective of the embodiment, the LED filament 1 is configured to, in operation, provide LED filament light 21, 22, and comprises an elongated carrier 3, a plurality of first LED light sources 4, a plurality of second LED light sources 5 and optionally an elongated encapsulant 6.

[0074] The elongated carrier 3 is light transmissive. The elongated carrier 3 comprises a first major surface 31 and a second major surface 32 opposite to the first major surface 31. The elongated carrier 3 may be a substrate such as a printed circuit board (PCB). The elongated carrier 3 may comprise electrical connection elements or wiring configured for providing electrical energy to the first and second plurality of LEDs 4 and 5. The elongated carrier 3 may be transparent. Alternatively, or additionally, the elongated carrier 3 may be provided with a light transmissivity of at least 80 %, at least 90 % or at least 95 %.

[0075] The plurality of first LED light sources 4 is configured to, in operation, emit first LED light source light 41. The plurality of first LED light sources 4 is arranged on the first major surface 31 of the elongated carrier 3. When in operation, the plurality of first LED light sources 4 emit at least a part, and optionally a majority or all, of the first LED light source light 41 in a first direction DI. A majority may in this connection be understood as at least 50 %, at least 60 %, at least 70 % or at least 80 % of the first LED light source light 41. The first direction DI may be understood as a main direction of emission of the first LED light source light 41. The first direction DI generally faces away from the first major surface 31. For instance, the first direction DI may be perpendicular to the first major surface 31. Alternatively, the first direction DI may be a direction forming an angle of, e.g., between 80 and 100 degrees with the first major surface 31. The plurality of first LED light sources 4 comprises a plurality of first LEDs.

[0076] The plurality of first LED light sources 4 may be top emitting LEDs. The top emitting LEDs may not emit light from their bottom. The top emitting LEDs may be arranged with their bottom surface on the first major surface 31 of the elongated carrier 3. A suitable example of a top emitting LED shown in Fig. 10A is a lateral wire-bonded LED chip 10 with a transparent top contact 11 and optionally with a bottom reflector 12. Another suitable example of a top emitting LED shown in Fig. 10B is a flip LED chip 10 with a bottom reflective contact 15. Yet another suitable example of a top emitting LED shown in Fig. 10C is a vertical thin film wire-bonded LED chip 10 with a reflective contact 17. It is noted in this context that “top” is to be understood as referring to a side of the LED chip 10 opposite to a substrate 13 on which the LED chip 10 is arranged. Likewise, “bottom” is to be understood as referring to a side of the LED chip 10 facing a substrate 13 on which the LED chip 10 is arranged. The LED chip 10 may be arranged on the substrate 13 by being attached or glued 14, directly or indirectly, e.g., with an intermediate layer such as the above-mentioned bottom reflector 12 or bottom reflective contact 15, and / or a conductive track 16.

[0077] The plurality of second LED light sources 5 is configured to, in operation, emit second LED light source light 51. The plurality of second LED light sources 5 is arranged on the first major surface 31 of the elongated carrier 3. When in operation, the plurality of second LED light sources 5 emit at least a part, and optionally a majority or all, of the second LED light source light 51 in a second direction D2. A majority may in this connection be understood as at least 50 %, at least 60 %, at least 70 % or at least 80 % of the second LED light source light 51. The second direction D2 may be understood as a main direction of emission of the second LED light source light 51. The second direction D2 generally faces away from the second major surface 32. The second direction D2 may be a direction opposite to the first direction DI. For instance, the second direction D2 may be perpendicular to the second major surface 32. Alternatively, the second direction D2 may be a direction forming an angle of, e.g., between 80 and 100 degrees with the second major surface 32. The plurality of second LED light sources 5 comprises a plurality of second LEDs.

[0078] The plurality of second LED light sources 5 may be wide-angle emitting LEDs, for instance with full width of half maximum for angular emission being larger than 120 degrees and preferably larger than 180. The plurality of second LED light sources 5 may be side emitting LEDs. Alternatively, or additionally, the plurality of second LED light sources 5 may be bottom emitting LEDs. The bottom emitting LEDs may not emit light from their top. The bottom emitting LEDs may be arranged with their bottom surface on the first major surface 31 of the elongated carrier 3. A suitable example of a bottom emitting LED shown in Fig. 11 A is a lateral wire-bonded LED chip 20 with a top transparent contact 71 and a reflective top layer 72. Another suitable example of a bottom emitting LED shown in Fig. 1 IB is a flip LED chip 20 comprising a top reflective contact 25 and being wire-bonded and glued to a transparent substrate 23. Yet another suitable example of a bottom emitting LED shown in Fig. 11C is a flip LED chip 20 with a top reflective layer 27 and a bottom transparent contact 28. It is noted in this context that “top” is to be understood as referring to a side of the LED chip 20 opposite to a substrate 23 on which the LED chip 20 is arranged. Likewise, “bottom” is to be understood as referring to a side of the LED chip 20 facing a substrate 23 on which the LED chip 20 is arranged. The LED chip 20 may be arranged on the substrate 23 by being attached or glued 24, directly or indirectly, e.g., with an intermediate layer such as the above-mentioned bottom transparent contact 28, contact points or bumps 29 or a conductive track 26.

[0079] In the embodiment shown in Figs. 1 to 3, the plurality of first LED light sources 4 and the plurality of second LED light sources 5 are arranged in an alternating configuration along a longitudinal axis LA of the LED filament 1.

[0080] The optional elongated encapsulant 6 encloses the plurality of first LED light sources 4 and the plurality of second LED light sources 5 at least partly, and optionally fully. The elongated encapsulant 6 covers the first major surface 31 and optionally also the second major surface 32 of the elongated carrier 3 at least partly, and optionally fully. The elongated encapsulant 6 comprises one or more of a luminescent material 7 (cf. Fig. 2) and a light scattering material 8 (cf. Fig. 3).

[0081] The LED filament light 21, 22 comprises first sub-LED filament light 21. At least 65 % and / or at most 90 % of the first LED light source light 41, which originates from the plurality of first LED light sources 4, forms the first sub-LED filament light 21. The first sub-LED filament light 21 is emitted in a third direction D3 facing away from the first major surface 31. The third direction D3 may be understood as a main direction of emission of the first sub-LED filament light 21. The third direction D3 and the first direction DI may be the same or may be mutually different directions.

[0082] The LED filament light 21, 22 further comprises second sub-LED filament light 22. At least 65 % and / or at most 90 % of the second LED light source light 51, which originates from the plurality of second LED light sources 5, forms the second sub-LED filament light 22. The second sub-LED filament light 22 is emitted in a fourth direction D4 facing away from the second major surface 32. The fourth direction D4 may be understood as a main direction of emission of the second sub-LED filament light 22. The fourth direction D4 and the second direction D2 may be the same or may be mutually different directions.

[0083] The first sub-LED filament light 21 is white light. The first sub-LED filament light 21 comprises a first correlated color temperature, CCT. The second sub-LED filament light 22 is white light. The second sub-LED filament light 22 comprises a second CCT. The second CCT is different from the first CCT. For instance, the second CCT may be different from the first CCT by 300 K or less, by 200 K or less or even by 100 K or less.

[0084] The LED filament 1 may further comprise an optional controller 9. The controller 9 is configured to individually control the first LED light source light 41 and the second LED light source light 51. The controller 9 may be configured to control or vary a luminous flux ratio between the first sub-LED filament light 21 and the second sub-LED filament light 22. In particular, the controller may control the first sub-LED filament light 21 having a first luminous flux (LF1) and the second sub-LED filament light 22 having a second luminous flux (LF2) wherein in an operational mode 0.9 < LF1 / LF2 < 1.1.

[0085] The controller 9 may also be configured to individually control the CCT of the first LED light source light 41 and the second LED light source light 51. The controller 9 may also be configured to individually control the intensity and / or the luminous flux of the first LED light source light 41 and the second LED light source light 51.

[0086] Figs. 4-6 show cross-sectional side views of another light emitting diode, LED, filament arrangement 200 according to the invention and comprising another LED filament 100. More particularly, Fig. 4 shows a longitudinal cross-sectional view of the LED filament arrangement 200, while Figs. 5 and 6 show transversal cross-sectional side views of the LED filament 100 as seen along the lines V-V and VI- VI, respectively, shown in Fig. 4. The LED filament 100 differs from the LED filament 1 described above and shown in Figs. 1-3 in virtue of the following features.

[0087] The plurality of first LED light sources 4 and the plurality of second LED light sources 5 are arranged parallel to each other as is most clearly visible in Figs. 5 and 6.

[0088] The optional elongated encapsulant 6 comprises at least two parts. As shown in Fig. 6, the elongated encapsulant 6 comprises a first part 61 and a second part 62. The first part 61 of the elongated encapsulant 6 encloses the plurality of first LED light sources 4 and the plurality of second LED light sources 5 at least partly, and optionally fully. The first part 61 of the elongated encapsulant 6 further covers the first major surface 31 of the elongated carrier at least partly, and optionally fully. The second part 62 of the elongated encapsulant 6 further covers the second major surface 32 of the elongated carrier at least partly, and optionally fully. The first part 61 and the second part 62 of the elongated encapsulant may comprise the same optical properties. Alternatively, the first part 61 and the second part 62 of the elongated encapsulant 6 may comprise mutually different optical properties. The optical properties may in this connection include light conversion, light scattering, light refraction, and light diffraction. The first part 61 may comprise a first green-yellow phosphor and a first red phosphor. The second part 62 may comprises a second green-yellow phosphor and a second red phosphor. The first part 61 may be configured to convert a majority of the first LED light source light 41 into first part converted light. The second part 62 may be configured to convert a majority of the second LED light source light 51 into second part converted light.

[0089] In an alternative shown in Fig. 5, the elongated encapsulant 6 comprises a first part 61, a second part 62, a third part 63 and a fourth part 64. The first part 61 of the elongated encapsulant 6 encloses the plurality of first LED light sources 4 at least partly, and optionally fully. The first part 61 of the elongated encapsulant 6 further covers a part of the first major surface 31 of the elongated carrier 3 adjacent to the plurality of first LED light sources 4 at least partly, and optionally fully. The third part 63 of the elongated encapsulant 6 encloses the plurality of second LED light sources 5 at least partly, and optionally fully. The third part 63 of the elongated encapsulant 6 further covers a part of the first major surface 31 of the elongated carrier 3 adjacent to the plurality of second LED light sources 5 at least partly, and optionally fully. The second part 62 of the elongated encapsulant 6 covers a part of the second major surface 32 of the elongated carrier 3 opposite to the plurality of first LED light sources 4 at least partly, and optionally fully. The fourth part 64 of the elongated encapsulant 6 covers a part of the second major surface 32 of the elongated carrier 3 opposite to the plurality of second LED light sources 5 at least partly, and optionally fully. The first part 61, the second part 62, the third part 63 and the fourth part 64 of the elongated encapsulant may comprise the same optical properties. Alternatively, the first part 61 and the second part 62 of the elongated encapsulant 6 may comprise optical properties being different from the optical properties of the third part 63 and the fourth part 64 of the elongated encapsulant 6.

[0090] In yet another alternative, the fourth part 64 of the elongated encapsulant 6 may be omitted, and the second part 62 of the elongated encapsulant 6 may cover a part of the second major surface 32 of the elongated carrier 3 opposite to the plurality of first LED light sources 4 and a part of the second major surface 32 of the elongated carrier 3 opposite to the plurality of second LED light sources 5 at least partly, and optionally fully.

[0091] Turning now to Fig. 7 it is shown that the plurality of second LED light sources 5 comprises a plurality of second LEDs, and that one or more of the second LEDs of the plurality of second LED light sources 5 may be covered by a light reflective layer 10. The light reflective layer 10 is configured to redirect the second LED light 51 in the second direction D2. The light reflective layer 10 may be a reflective coating or a reflective foil. The light reflective layer 10 may comprise a reflectance of at least 90 %, at least 95 % or at least 99 %. A light reflective layer 10 may be added to any of the above described possible LED filaments 1, 100. When a light reflective layer 10 is present, the elongated encapsulant 6, or the first part 61 or the third part 63 of the elongated encapsulant 6 as the case may be, covers the reflective layer 10 at least partially, and optionally fully. When a light reflective layer 10 is present, it becomes possible to provide the plurality of second LEDs as top emitting LEDs, for instance of one of the types described further above.

[0092] Fig. 8 shows an exemplary lamp 300 comprising a LED filament arrangement 200 according to any embodiment of the invention. In the embodiment shown, the LED filament arrangement 200 comprises a substantially straight LED filament 1; 100. The LED filament arrangement 200 of such a lamp may in other embodiments comprise a LED filament 1; 100 with another shape, such as, but not limited to, spiral-shaped, helix-shaped, meandering, twisted, flat and combinations thereof.

[0093] The lamp 300 further comprises a driver or controller 305 configured for controlling the plurality of LEDs 4 of the LED filament arrangement 200. The controller 305 is configured to power the plurality of LEDs 4 via electrical circuitry (not visible on the figures) of the LED filament arrangement 200. The LED filament arrangement 200 may also comprise a controller 9, which may or may not be separate from the controller 305. In other words, the controller 305 and the controller 9 of the LED filament arrangement 200 may be integrated into one and the same driver or controller, or they may be mutually separate units.

[0094] The lamp 300 further comprises an envelope 301 at least partially enveloping the at least one LED filament arrangement 200. The lamp 300 further comprises a cap 303. As shown in Fig. 8, the controller 305 is arranged within the envelope 301. When comprising a cap 303, the controller 305 may also be arranged inside the cap 303 such that it is hidden from view. The lamp 300 further comprises threading 302 for connection to a socket, and a terminal 304 for connection to a source of electrical energy.

[0095] The envelope 301 of the lamp 300 may further and optionally be provided with a coating (not shown), such as a reflective coating, covering at least a part of the envelope 301.

[0096] Turning finally to Fig. 9, an exemplary luminaire in the form of a pendant 400 is shown. The pendant 400 comprises a LED filament arrangement 200 according to any embodiment of the invention. The LED filament arrangement 200 is as shown in Fig. 9 provided within a lamp 300 in the form of a light bulb. The LED filament arrangement 200 as shown in Fig. 9 comprises a substantially straight LED filament 1; 100.

[0097] As is also mentioned above, the light bulb further comprises a transparent envelope (cf. transparent envelope 301 of lamp 300) at least partially enveloping the at least one LED filament arrangement 200. The transparent envelope may be shaped in any feasible shape, for example such as to resemble the shape of any one of a standard light bulb, a globe light bulb, a candlelight bulb, a customized light bulb and even a spiral light bulb. The transparent envelope may comprise a luminescent material. The transparent envelope may be a glass envelope.

[0098] The pendant 400 further comprises a socket 401 for connecting the lamp 300, and thereby the LED filament arrangement 200, to the pendant 400. The socket 401 is adapted to cooperate with the base 303 of the lamp 300. The socket 401 may comprise a threading adapted to cooperate with the threading 302 of the lamp 300. The socket 401 may comprise a terminal adapted to cooperate with the terminal 304 of the lamp 300. The pendant 400 further comprises a reflector or screen 403.

[0099] The pendant 400 may further comprise a driver 402 configured for controlling the LED filament arrangement 200. The driver 402 may or may not be the same unit as the controller 305 described above. In other words, the driver 402 and the controller 305 may be integrated into one and the same driver or controller, or they may be mutually separate units. Alternatively, or additionally, the LED filament arrangement 200 may also comprise a controller 9, which may or may not be separate from one or both of the driver 402 and the controller 305.

[0100] As shown in Fig. 9, the driver 402 is arranged on a reflector or screen 403 of the pendant 400. The driver may also be arranged within or incorporated into the reflector or screen 403. The pendant 400 further comprises an electrical wiring 404 for connection to a source of electricity, such as a mains.

[0101] It is noted that the pendant 400 shown in Fig. 9 is only one example of a luminaire according to the invention. Any suitable type of luminaire may be envisaged, such as but not limited to, a standing luminaire, a wall hung luminaire, a chandelier, a reading luminaire, an outdoor luminaire, and a table luminaire.

[0102] 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.

[0103] Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.

Claims

CLAIMS:

1. A light emitting diode, LED, filament arrangement (200) comprising a LED filament (1; 100) configured to, in operation, provide LED filament light (21, 22), the LED filament comprising: an elongated carrier (3) being light transmissive and comprising a first major surface (31) and a second major surface (32) opposite to the first major surface, a plurality of first LED light sources (4) configured to, in operation, emit first LED light source light (41) and being arranged on the first major surface (31) of the elongated carrier, and a plurality of second LED light sources (5) configured to, in operation, emit second LED light source light (51) and being arranged on the first major surface (31) of the elongated carrier, wherein the plurality of first LED light sources (4) is configured to emit, in operation, at least a part of the first LED light source light (41) in a first direction (DI) facing away from the first major surface (31), and the plurality of second LED light sources (5) is configured to emit, in operation, at least a part of the second LED light source light (51) in a second direction (D2), opposite to the first direction, facing away from the second major surface (32), wherein the LED filament light (21, 22) comprises first sub-LED filament light (21) emitted in a direction facing away from the first major surface (31) and second sub- LED filament (22) light emitted in a direction facing away from the second major surface (32) and at least partly passing through the elongated carrier (3) and, wherein the plurality of first LED light sources (4) is configured to emit, in operation, a majority of the first LED light source light (41) in the first direction (DI), and the plurality of second LED light sources (5) are configured to emit, in operation, a majority of the second LED light source light (51) in the second direction (D2).

2. A LED filament arrangement according to claim 1, wherein the plurality of first LED light sources (4) and the plurality of second LED light sources (5) are arranged: in an alternating configuration, orparallel to each other.

3. A LED filament arrangement according to any one of the above claims, wherein the elongated carrier (3) is one or more of transparent and having a light transmissivity of at least 80 %.

4. A LED filament arrangement according to any one of the above claims, and further comprising an elongated encapsulant (6) at least partly enclosing the plurality of first LED light sources and the plurality of second LED light sources, the elongated encapsulant at least partly covering the first major surface (31), and the elongated encapsulant comprising one or more of a luminescent material (7) and a light scattering material (8).

5. A LED filament arrangement according to any one of the above claims, wherein the first sub-LED filament light (21) is white light having a first correlated color temperature, CCT, and the second sub-LED filament light (22) is white light having a second CCT, the second CCT being different from the first CCT by at least 300K.

6. A LED filament arrangement according to any one of claims 1 to 4, wherein the first sub-LED filament light (21) is white light having a first CCT and the second sub- LED filament light (22) is white light having a second CCT, the second CCT being different from the first CCT by 300 K or less.

7. A LED filament arrangement according to any one of the above claims, wherein one or more of the following applies: the plurality of first LED light sources (4) comprises a plurality of first LEDs, and the plurality of first LEDs (4) comprises top emitting LEDs, and the plurality of second LED light sources (5) comprises a plurality of second LEDs, and the plurality of second LEDs (5) comprises one or more of side emitting LEDs and bottom emitting LEDs.

8. A LED filament arrangement according to any one of the above claims, wherein the plurality of second LED light sources (5) comprises a plurality of second LEDs, wherein the plurality of second LEDs comprises top emitting LEDs, and wherein the topemitting LEDs are covered by a light reflective layer (10) configured to redirect the second LED light (51) in the second direction (D2).

9. A LED filament arrangement according to any one of the above claims, wherein one or more of the following applies: at least 65 % of the first LED light source light (41), which originates from the plurality of first LED light sources (4), forms the first sub-LED filament light (21), and at most 95 % of the first LED light source light (41), which originates from the plurality of first LED light sources (4), forms the first sub-LED filament light (21).

10. A LED filament arrangement according to any one of the above claims, wherein one or more of the following applies: at least 65 % of the second LED light source light (51), which originates from the plurality of second LED light sources (5), forms the second sub-LED filament light (22), and at most 95 % of the second LED light source light (51), which originates from the plurality of second LED light sources (5), forms the second sub-LED filament light (22).

11. A LED filament arrangement according to any one of the above claims, wherein the elongated encapsulant (6) comprises a first part (61) and a second part (62), the first part (61) at least partly enclosing the plurality of first LED light sources and the plurality of second LED light sources, the first part (61) of the elongated encapsulant at least partly covering the first major surface (31), and the second part (62) at least partly covering the second major surface (32).

12. A LED filament arrangement according to any one of the above claims, wherein the first sub-LED filament light (21) has a first luminous flux (LF1) and the second sub-LED filament light (22) has a second luminous flux (LF2) wherein in an operational mode 0.9 < LF1 / LF2 < 1.1.

13. A LED filament arrangement according to any one of the above claims, and further comprising a controller (9) configured to individually control the first LED light source light (41) emitted by the plurality of first LED light sources (4) and the second LED light source light (51) emitted by the plurality of second LED light sources (5) such that aluminous flux ratio between the first sub-LED filament light and the second sub-LED filament light is varied.

14. A luminaire (400) or a LED filament lamp (300) comprising a LED filament arrangement (200) according to any one of claims 1 to 13.

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