A LED filament lamp

Abstract

A LED filament lamp (1) configured to, in operation, provide LED filament lamp light (8), and having a central lamp axis (CLA) and comprising a plurality of first LED filaments (3), each first LED filament (31-34) being an elongated element comprising a first length (L1) extending in a longitudinal direction (LD), a first width (W1) extending perpendicular to the longitudinal direction (LD), a first thickness (T1) extending perpendicular to the longitudinal direction (LD) and perpendicular to the first width (W1), and a first aspect ratio (AR1), where AR1 = W1 / T1 and a plurality of second LED filaments (4), each second LED filament (41-44) being an elongated element comprising a second length (L2) extending in a longitudinal direction (LD), a second width (W2) extending perpendicular to the longitudinal direction (LD), a second thickness (T2) extending perpendicular to the longitudinal direction (LD) and perpendicular to the second width (W2), and a second aspect ratio (AR2), where AR2 = W2 / T2. Each first LED filament is configured to, in operation, provide first LED filament light (6) with a first luminous flux (LF1), each second LED filament is configured to, in operation, provide second LED filament light (7) with a second luminous flux (LF2), and the second aspect ratio (AR2) is at least two times larger than the first aspect ratio (AR1).

Description

[0001] A LED FILAMENT LAMP

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a LED filament lamp comprising at least one first LED filament and at least one second LED filament.

[0004] BACKGROUND OF THE INVENTION

[0005] A trend in lighting is LED filament lamps. An LED filament lamp is an LED lamp which is designed to resemble a traditional incandescent light bulb with a visible filament for aesthetic and light distribution purposes, but with the high efficiency of lightemitting diodes.

[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 carrier comprises a first major surface and an opposite second major surface, the LEDs are arranged on at least one of these surfaces. The carrier may be reflective or 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 LED light into converted light. The luminescent material may be a phosphor such as an inorganic phosphor and / or quantum dots or rods (QDs). The LED filament may comprise multiple sub-filaments.

[0010] US 2022 / 0186890 Al discloses a lamp, comprising a lamp base, a semi- reflective envelope, at least one first solid state light source filament arranged inside the semi-reflective envelope, and a second solid state light source arranged inside the semi- reflective envelope. The reflectivity of the semi-reflective envelope is in the range from 30% to 70% for light emitted by the at least one first solid state light source filament and the second solid state light source. The at least one first solid state light source filament is arranged at a first distance lower than 7 millimeters from the semi-reflective envelope, and the second solid state light source is arranged at second distance higher than 15 millimeters from the semi-reflective envelope.

[0011] It is desired to improve the performance, functionality and / or appearance of LED filament lamps.

[0012] SUMMARY OF THE INVENTION

[0013] It is an object of the present invention to overcome this problem, and to provide a LED filament lamp with one or more of an improved performance, an improved functionality, and an improved appearance.

[0014] According to a first aspect of the invention, this and other objects are achieved by means of a LED filament lamp configured to, in operation, provide lamp light, the LED filament lamp having a central lamp axis, CLA, and comprising at least one first LED filament, each first LED filament being an elongated element comprising a first length, LI, extending in a longitudinal direction, LD, a first width W 1 extending perpendicular to the longitudinal direction, LD, a first thickness, Tl, extending perpendicular to the longitudinal direction, LD, and perpendicular to the first width, Wl, and a first aspect ratio, ARI, where ARI = Wl / Tl, and at least one second LED filament, each second LED filament being an elongated element comprising a second length, L2, extending in a longitudinal direction, LD, a second width, W2, extending perpendicular to the longitudinal direction, LD, a second thickness, T2, extending perpendicular to the longitudinal direction, LD, and perpendicular to the second width, W2, and a second aspect ratio, AR2, where AR2 = W2 / T2, where each first LED filament is configured to, in operation, provide first LED filament light with a first luminous flux, LF1, where each second LED filament is configured to, in operation, provide second LED filament light with a second luminous flux, LF2, and where the second aspect ratio, AR2, is at least two times larger than the first aspect ratio, ARI. Thereby, and in particular by providing at least one first LED filament configured to, in operation, provide first LED filament light with a first luminous flux, LF1, and at least one second LED filament configured to, in operation, provide second LED filament light with a second luminous flux, LF2, and that the second aspect ratio, AR2, of the at least one second LED filament is at least two times larger than the first aspect ratio, ARI, of the at least one first LED filament, a LED filament lamp with at least one of an improved performance, an improved functionality, and an improved appearance is provided for, both when the LED filament lamp is operated to provide a low lumen light output and when the LED filament lamp is operated to provide a high lumen light output.

[0015] The first aspect ratio, ARI, may be chosen such that 2 > ARI > 0.5.

[0016] The second aspect ratio, AR2, may be chosen such that 8 > AR2 > 2.5.

[0017] The respective thicknesses T1 and T2 may be chosen such that and 1.5 > Tl / T2 > 0.5.

[0018] Each of the above three embodiments provide for a LED filament lamp with a further improved the performance, functionality and / or appearance both in case of a low lumen light output and a high lumen light output.

[0019] The length ratio between the first length, LI, of each first LED filament the second length, L2, of each second LED filament is defined as L1 / L2 and may be chosen such that 0.8 < L1 / L2 < 1.2.

[0020] Each first LED filament comprises a plurality of first LEDs and each second LED filament comprises a plurality of second LEDs, where the second plurality of LEDs may comprise at least 1.5 times more LEDs than the first plurality of LEDs.

[0021] The ratio between the first luminous flux, LF1, and the second luminous flux, LF2, is defined as LF1 / LF2 and may be chosen such that LF1 / LF2 < 0.5.

[0022] Each of the above three embodiments provide for a LED filament lamp with a further improved the functionality and / or appearance.

[0023] The at least one first LED filament and the at least one second LED filament may be arranged along the central lamp axis, CLA, and altematingly and evenly distributed around the central lamp axis, CLA.

[0024] It is noted that in this connection “along” is intended to mean in an angle of less than + / - 20 degrees with the central lamp axis, CLA.

[0025] Thereby, a LED filament lamp with a particularly uniform light output and thus a further improved appearance is provided for. The at least one first LED filament is / are arranged in a first distance, DI, from the central lamp axis, CLA, and the at least one second LED filament is / are arranged in a second distance, D2, from the central lamp axis, CLA, and the distances DI and D2 may be chosen such that DI > D2.

[0026] The obtained effect is improved decorative lighting. The reason is that the low aspect ratio filaments are used at a low luminous flux level and when the second LED filaments are off, the first LED filaments will not irradiate the larger second LED filament which may be visualized due to this light, e.g., through phosphor conversion, i.e., crosstalk.

[0027] Spacings may be provided in a tangential direction between adjacent LED filaments, and the spacings may have a size or width being in a range of at least two times W 1 and at most two times W2.

[0028] Thereby, a LED filament lamp with a particularly uniform light output and thus a further improved appearance is provided for, even when one of the first and second plurality of LED filaments are turned off and do not emit light.

[0029] Each first LED filament may comprise a first plurality of LEDs arranged on a first elongated carrier, where a first elongated encapsulant is covering the first plurality of LEDs, the first elongated encapsulant comprises a first luminescent material configured to at least partly convert first LED light emitted by the first plurality of LEDs into first converted light and / or a first light scattering material configured to at least partly scatter first LED light emitted by said first plurality of LEDs into first scattered light, each second LED filament may comprise a second plurality of LEDs arranged on a second elongated carrier, where a second elongated encapsulant is covering the second plurality of LEDs, the second elongated encapsulant comprises a second luminescent material configured to at least partly convert second LED light emitted by the second plurality of LEDs into second converted light and / or a second light scattering material configured to at least partly scatter second LED light emitted by said second plurality of LEDs into second scattered light, and / or (i) the thickness, TC2, of the second elongated carrier is higher than the thickness, TCI, of the first elongated carrier and / or (ii) the material of the second elongated carrier has a higher thermal conductivity than the material of the first elongated carrier.

[0030] Thereby, and in particular by providing that the thickness, TC2, of the second elongated carrier is higher than the thickness, TCI, of the first elongated carrier and / or the material of the second elongated carrier has a higher thermal conductivity than the material of the first elongated carrier, a LED filament lamp with a particularly good heat dissipation and thus prolonged lifetime is provided for. By further providing encapsulants, the LEDs are protected against external influences by the encapsulant, thus providing a more robust LED filament lamp, and a more uniform LED filament lamp light output is ensured.

[0031] The light transmissivity of the second elongated carrier may be lower than the light transmissivity of the first elongated carrier. The light reflectivity of the second elongated carrier may be higher than the light reflectivity of the first elongated carrier.

[0032] Thereby, a LED filament lamp with a particularly uniform light output and thus a further improved functionality and appearance is provided for, particularly when both of the first and second plurality of LED filaments are turned on and emit light.

[0033] The first plurality of LEDs may be arranged in a first array having a single column and the second plurality of LEDs may be arranged in a second array having a plurality of columns.

[0034] Thereby, a LED filament lamp with a particularly uniform light output and thus a further improved functionality and appearance is provided for, particularly when both of the first and second plurality of LED filaments are turned on and emit light.

[0035] Each first LED filament may comprise a first plurality of LEDs arranged on a first elongated carrier, where a first elongated encapsulant is covering the first plurality of LEDs, and the first elongated encapsulant comprises a first luminescent material configured to at least partly convert first LED light emitted by the first plurality of LEDs into first converted light, each second LED filament may comprise a second plurality of LEDs arranged on a second elongated carrier, where a second elongated encapsulant is covering the second plurality of LEDs, and the second elongated encapsulant comprises a second luminescent material configured to at least partly convert second LED light emitted by the second plurality of LEDs into second converted light; and where one or more of the following may apply:

[0036] (i) the thickness, TE1, of the first encapsulant is lower than the thickness, TE2, of the second encapsulant, and

[0037] (ii) the concentration of the first luminescent material in the first encapsulant is lower than the concentration of the second luminescent material in the second encapsulant, and

[0038] (iii) the first luminescent material is of a first type, Pl, and the second luminescent material is of a second type, P2, where the second type, P2, is different from the first type PL

[0039] Thereby, a LED filament lamp with a particularly uniform light output and thus a further improved functionality and performance is provided for, particularly in terms of allowing a variety of differently customized and / or possible light outputs. Each first LED filament may be configured to provide the first LED filament light with a first correlated color temperature, CCT1, of less than or equal to 2500 K, and each second LED filament may be configured to provide the second LED filament light with a second correlated color temperature, CCT2, of more than or equal to 3000 K.

[0040] Thereby, a LED filament lamp with a further improved appearance is provided for, particularly when both of the first and second plurality of LED filaments are turned on and emit light.

[0041] The first length, LI, of each first LED filament may be different from the second length, L2, of each second LED filament.

[0042] Thereby, a LED filament lamp with a further improved appearance is provided for, particularly when both of the first and second plurality of LED filaments are turned on and emit light.

[0043] The first and second LED filaments may be arranged next to each other with respect to the longitudinal direction.

[0044] The first and second LED filaments may be arranged in a mutually shifted position with respect to each other in the longitudinal direction.

[0045] The LED filament lamp may comprise at least one first LED filament and a plurality of second LED filaments.

[0046] The LED filament lamp may comprise at least one second LED filament and a plurality of first LED filaments.

[0047] The LED filament lamp may comprise a plurality of first LED filaments and a plurality of second LED filaments.

[0048] The LED filament lamp may further comprise a controller, and the controller is configured to one or both of dimming and brightening the at least one second LED filament and dimming and brightening the at least one first LED filament.

[0049] Thereby, a LED filament lamp with a further improved functionality and performance is provided for, both when one of the at least one first and the at least one second LED filament are turned off and do not emit light, and when both of the at least one first and at least one second LED filament are turned on and emit light.

[0050] The controller may further be configured to dimming the at least one second LED filament until the second LED filament light is provided with a second luminous flux being equal to the first luminous flux.

[0051] Thereby, a LED filament lamp with a further improved appearance, functionality and performance is provided for, especially in the transition between both at the least one first and at least one second LED filament being turned on and the at least one second LED filament being turned off while the at least one first LED filament are still turned on.

[0052] The controller may further be configured to switch off the at least one second LED filament and switch on the at least one first LED filament when the at least one second LED filament is dimmed to provide the second LED filament light with a second luminous flux being lower than the first luminous flux.

[0053] Thereby, a LED filament lamp with a further improved appearance, functionality and performance is provided for, especially when the at least one second LED filament is being or has been dimmed to provide the second LED filament light with a second luminous flux being lower than the first luminous flux.

[0054] The controller may further be configured to dimming the at least one first LED filament when the at least one second LED filament is switched off and the at least one first LED filament is switched on.

[0055] The controller may further be configured to brightening the at least one first LED filament when the at least one second LED filament is switched off and the at least one first LED filament is switched on.

[0056] Thereby, a LED filament lamp with a further improved appearance, functionality and performance is provided for, especially for LED lamp light outputs with a very low luminous flux.

[0057] The controller may further be configured to switch on the at least one second LED filament and switch off the at least one first LED filament when the at least one first LED filament is brightened to provide the first LED filament light with a first luminous flux being at an upper threshold value of the first luminous flux.

[0058] Thereby, a LED filament lamp with a further improved appearance, functionality and performance is provided for, especially in the transition between the at least one second LED filament being turned off while the at least one first LED filament are still turned on and both the at least one first and the at least one second LED filament being turned on.

[0059] The controller may further be configured to brighten the at least one second LED filament until the second LED filament light is provided with a second luminous flux having a desired value being larger than an upper threshold value of the first luminous flux. Thereby, a LED filament lamp with a further improved appearance, functionality and performance is provided for, especially for LED lamp light outputs with a very high luminous flux.

[0060] The controller may further be configured to gradually change one or both of the first correlated color temperature, CCT1, and the second correlated color temperature, CCT2.

[0061] Thereby, a LED filament lamp is provided with which it becomes possible to provide LED lamp light with different colors as may be desired without adversely affecting the appearance, functionality and performance of the LED filament lamp.

[0062] The invention further relates to a luminaire comprising at least one LED filament lamp according to the invention.

[0063] It is noted that the invention relates to all possible combinations of features recited in the claims.

[0064] BRIEF DESCRIPTION OF THE DRAWINGS

[0065] 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.

[0066] Fig. 1 shows a schematic cross-sectional top view of an embodiment of a LED filament lamp according to the invention and comprising a plurality of first LED filaments and a plurality of second LED filaments.

[0067] Fig. 2 shows a schematic cross-sectional top view of another embodiment of a LED filament lamp according to the invention.

[0068] Fig. 3 shows a schematic cross-sectional side view of the LED filament lamp according to Fig. 2.

[0069] Fig. 4 shows a schematic cross-sectional side view of a first LED filament of the plurality of first LED filaments.

[0070] Fig. 5 shows a schematic cross-sectional side view of a second LED filament of the plurality of second LED filaments.

[0071] Fig. 6 shows a cross-sectional side view of a luminaire comprising a LED filament lamp according to the invention.

[0072] 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. DETAILED DESCRIPTION

[0073] 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.

[0074] Fig. 1 shows a schematic cross-sectional top view of an embodiment of a LED filament lamp 1 according to the invention. The LED filament lamp 1 is configured to, in operation, provide LED filament lamp light 8. The LED filament lamp 1 comprises a central lamp axis CLA. Generally, and irrespective of the embodiment, the LED filament lamp 1 further comprises at least one first LED filament 3 and at least one second of LED filament 4. In the specific embodiment shown in Fig. 1, the LED filament lamp 1 comprises a plurality of first LED filaments 3 and a plurality of second of LED filaments 4.

[0075] The first plurality of LED filaments 3 comprises a number, N, of first LED filaments, where N is an integer being larger than one. In the embodiment shown in Fig. 1, there is provided three first LED filaments 31, 32, 33. Generally, and irrespective of the embodiment, each first LED filament 31-33 is an elongated element comprising a first length, LI, extending in a longitudinal direction LD, a first width, Wl, extending perpendicular to the longitudinal direction, LD, and a first thickness, Tl, extending perpendicular to the longitudinal direction, LD, and perpendicular to the first width, W 1. The longitudinal direction LD extends in parallel with the central lamp axis CLA. Each first LED filament 31- 33 further comprises a first aspect ratio, ARI, defined as ARI = Wl / Tl. Each first LED filament 31-33 is configured to, in operation, provide first LED filament light 6 with a first luminous flux, LF 1.

[0076] The second plurality of LED filaments 4 comprises a number, M, of second LED filaments, where M is an integer being larger than one. It is noted that N may be equal to M or that N may be different from M. In alternative embodiments it is even possible that M and / or N may be equal to one. In the embodiment shown in Fig. 1, there is provided three second LED filaments 41, 42, 43. Generally, and irrespective of the embodiment, each second LED filament 41-43 is an elongated element comprising a second length, L2, extending in a longitudinal direction, LD, a second width, W2, extending perpendicular to the longitudinal direction, LD, and a second thickness, T2, extending perpendicular to the longitudinal direction, LD, and perpendicular to the second width, W2. Each second LED filament 41-43 further comprises a second aspect ratio, AR2, defined as AR2 = W2 / T2. Each second LED filament is configured to, in operation, provide second LED filament light 7 with a second luminous flux, LF2.

[0077] Generally, and irrespective of the embodiment, the second aspect ratio, AR2, is at least two times larger than the first aspect ratio, ARI. The first aspect ratio Al may be chosen such that 2 > ARI > 0.5. The second aspect ratio A2 may be chosen such that 8 > AR2 > 2.5.

[0078] The first thickness T1 and the second thickness T2 may be chosen such that 1.5 > T1 / T2 > 0.5. The first length LI and the second length L2 may be chosen such that the length ratio between the first length LI of each first LED filament 31-33 and the second length L2 of each second LED filament 41-43, which is defined as L1 / L2, fulfills the relation 0.8 < L1 / L2 < 1.2.

[0079] The first width W1 may be in a range from 1 to 4 mm. The first thickness T1 may be in a range from 1 to 4 mm. The first length LI may be in a range from 4 to 20 cm. The second width W2 may be in a range from 5 to 20 mm. The second thickness T2 may be in a range from 1 to 5 mm. The second length L2 may be in a range from 4 to 20 cm. By way of an example, the first width W 1 may be 3 mm, the first thickness T1 may be 3 mm and the first length LI may be 8 cm, while the second width W2 may be 10 mm, the second thickness T1 may be 3 mm and the second length L2 may be 8 cm.

[0080] The first luminous flux LF1 and the second luminous flux LF2 may be chosen such that the ratio between the first luminous flux LF1 and the second luminous flux LF2, which is defined as LF1 / LF2, fulfills the relation LF1 / LF2 < 0.5.

[0081] As shown in Figs. 1 and 3, the LED filaments 31-33 of the first plurality of LED filaments 3 and the LED filaments 41-43 of the second plurality of LED filaments 4 are arranged along the central lamp axis CLA - cf. also Fig. 3. By “along” is in this connection meant that the LED filaments 31-33 of the first plurality of LED filaments 3 and the LED filaments 41-43 of the second plurality of LED filaments 4 are arranged such that their respective length dimension LI and L2 extends in an angle of maximally 20 degrees with the central lamp axis CLA. In Fig. 3 the said angle is shown as being zero degrees. Furthermore, the LED filaments 31-33 of the first plurality of LED filaments 3 and the LED filaments 41- 43 of the second plurality of LED filaments 4 are arranged alternatingly and evenly distributed around the central lamp axis CLA. Furthermore, as may also be seen in Fig. 1, the plurality of first LED filaments 3 are arranged in a first distance DI from the central lamp axis CL A, and the plurality of second LED filaments 4 are arranged in a second distance D2 from the central lamp axis CLA. The first distance DI and the second distance D2 may be chosen such that DI is larger than D2. Also, spacings S are provided in a tangential direction between adjacent LED filaments 31-33 and 41-43. The spacings S may be chosen to have a size or width being in a range of at least two times the first width W 1 and at most two times the second width W2.

[0082] Fig. 2 shows a schematic cross-sectional top view of another embodiment of a LED filament lamp 100 according to the invention. The LED filament lamp 100 differs from the LED filament lamp 1 shown in Fig. 1 and described above in virtue only of the particular arrangement of the LED filaments 31-34 of the first plurality of LED filaments 3 and the LED filaments 41-43 of the second plurality of LED filaments 4 with respect to one another, as well as the number of LED filaments 31-34 of the first plurality of LED filaments 3 provided.

[0083] Particularly, Fig. 2 illustrates a configuration in which the LED filaments 31- 34 of the first plurality of LED filaments 3 and the LED filaments 41-43 of the second plurality of LED filaments 4 are arranged such that the LED filaments 31-34 of the first plurality of LED filaments 3, which emit the first LED filament light 6 with the first lower luminous flux LF1, are arranged around the LED filaments 41-43 of the second plurality of LED filaments 4, which emit the second LED filament light 7 with the second higher luminous flux LF2. Also, three LED filaments 41-43 of the second plurality of LED filaments 4 and four LED filaments 31-34 of the first plurality of LED filaments 3 are provided for

[0084] Referring now also to Fig. 4, each first LED filament 31-34 comprises a first plurality of LEDs 310 arranged on a first elongated carrier 311. The first plurality of LEDs 310 may be arranged in a first array having a single column. The first elongated carrier 311 extends, when the first LED filament 31 is mounted in a LED filament lamp 1 according to the invention, in the longitudinal direction LD. The first elongated carrier 311 comprises a first carrier thickness TC 1. The first elongated carrier 311 comprises a first maj or surface 315 and a second major surface 316 opposite to the first major surface 315. The first plurality of LEDs 310 may be arranged on the first major surface 315 and / or on the second major surface 316. The first plurality of LEDs 310 are configured to, in operation, emit first LED light. Each first LED filament 31-34 is configured to, in operation, emit first LED filament light 6 consisting of first LED light. For instance, each first LED filament 31-33 may be configured to provide the first LED filament light 6 with a first correlated color temperature CCT1 of less than or equal to 2500 K.

[0085] Each first LED filament 31-34 may further comprise a first elongated encapsulant 312. The first elongated encapsulant 312 is arranged to cover the first plurality of LEDs 310. The first elongated encapsulant 312 comprises a first encapsulant thickness TEL The first elongated encapsulant 312 may comprise a first luminescent material 313. The first luminescent material 313 is configured to at least partly convert first LED light emitted by the first plurality of LEDs 310 into first converted light. Alternatively, or additionally, the first elongated encapsulant 312 may comprise a first light scattering material 314. The first light scattering material 314 is configured to at least partly scatter first LED light emitted by said first plurality of LEDs into first scattered light.

[0086] In the embodiment shown in Fig. 4, the first plurality of LEDs 310 are arranged on the first maj or surface 315 of the first carrier 311. The first LED filament 31 may further comprise a further elongated encapsulant 317 arranged on the second major surface 316. The further elongated encapsulant 317 may be the same as or different from the first elongated encapsulant 312.

[0087] Referring now also to Fig. 5, each second LED filament 41-43 comprises a second plurality of LEDs 410 arranged on a second elongated carrier 411. The second plurality of LEDs 410 may be arranged in a second array having a plurality of columns. The second plurality of LEDs 410 may comprise at least 1.5 more LEDs than the first plurality of LEDs 310. The second elongated carrier 411 extends, when the second LED filament 41 is mounted in a LED filament lamp 1 according to the invention, in the longitudinal direction LD. The second elongated carrier 411 comprises a second carrier thickness TC2.The second elongated carrier 411 comprises a first major surface 415 and a second major surface 416 opposite to the first major surface 415. The second plurality of LEDs 410 may be arranged on the first major surface 415 and / or on the second major surface 416. The second plurality of LEDs 410 are configured to, in operation, emit second LED light. Each second LED filament 41-43 is configured to, in operation, emit second LED filament light 7 consisting of second LED light. For instance, each second LED filament 41-43 may be configured to provide the second LED filament light 7 with a second correlated color temperature CCT2 of more than or equal to 3000 K.

[0088] The LED filament lamp 1 is as mentioned configured to, in operation, emit LED filament lamp light 8. The LED filament lamp light 8 comprises at least one of first LED filament light 6 and second LED filament light 7. The LED filament lamp light 8 may be white LED filament lamp light having a correlated color temperature in a range from 1700K to 6500K and / or a color rendering index of at least 80.

[0089] Each second LED filament 41-43 may further comprise a second elongated encapsulant 412. The second elongated encapsulant 412 is arranged to cover the second plurality of LEDs 410. The second elongated encapsulant 412 comprises a second encapsulant thickness TE2. The second elongated encapsulant 412 may comprise a second luminescent material 413. The second luminescent material 413 is configured to at least partly convert second LED light emitted by the second plurality of LEDs 410 into second converted light. Alternatively, or additionally, the second elongated encapsulant 412 may comprise a second light scattering material 414. The second light scattering material 414 is configured to at least partly scatter second LED light emitted by said second plurality of LEDs into second scattered light.

[0090] In the embodiment shown in Fig. 5, the second plurality of LEDs 410 are arranged on the first major surface 415 of the second carrier 411. The second LED filament 41 may further comprise a further elongated encapsulant 417 arranged on the second major surface 416. The further elongated encapsulant 417 may be the same as or different from the second elongated encapsulant 412.

[0091] The second carrier thickness TC2 of the second elongated carrier 411 may be larger than the first carrier thickness TC 1 of the first elongated carrier 311. Alternatively, or additionally, the material of the second elongated carrier 411 may comprise a higher thermal conductivity than the thermal conductivity of the material of the first elongated carrier 311. Alternatively, or additionally, the light transmissivity of the second elongated carrier 411 may be lower than the light transmissivity of the first elongated carrier 311.

[0092] The first encapsulant thickness TE1 of the first encapsulant 312 may be lower than the second encapsulant thickness TE2 of the second encapsulant 412. Alternatively, or additionally, the concentration of the first luminescent material 313 in the first encapsulant 312 may be lower than the concentration of the second luminescent material 413 in the second encapsulant 412. Alternatively, or additionally, the first luminescent material 313 may be of a first type, Pl, the second luminescent material 413 may be of a second type, P2, and the second type, P2, is different from the first type, PL

[0093] Referring now specifically to Fig. 3, the LED filament lamp 1; 100 further comprises a translucent envelope 2 at least partially enveloping the at least one LED filament arrangement. The translucent envelope 2 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 translucent envelope 2 may comprises a luminescent material. The translucent envelope 2 may be a glass envelope.

[0094] The LED filament lamp 1; 100 further comprises a base 9, such as a cap. The translucent envelope 2 is connected to or mounted on the base 9. The base 9 is configured to connect the LED filament lamp 1; 100 electrically and mechanically to a socket of a luminaire (cf. Fig. 6). The translucent envelope 2 may comprise a neck, and where provided, the neck forms the part of the translucent envelope 2 that is connected or attached to the base 9.

[0095] The LED filament lamp 1; 100 may further comprise threading 10 for connection to a socket and a terminal 11 for connection to a source of electrical energy. The threading 10 and the terminal 11 may form part of or be provided on the base 9.

[0096] The LED filament lamp 1; 100 may further optionally comprise a driver or controller 5 configured for controlling the LED filament lamp 1; 100. The driver or controller 5 may be an external unit, a unit arranged within the LED filament lamp 1; 100 as shown on Fig. 3 or a combination of both such units.

[0097] The LED filament lamp 1; 100 may further comprise an exhaust tube 12. The exhaust tube 12 is arranged, preferably centrally, in a stem 13 of the LED filament lamp 1; 100. The exhaust tube 12 is configured for sealing a gas between the translucent envelope 2 and the exhaust tube 12. The controller 5 may be arranged between the translucent envelope 2 and the exhaust tube 12.

[0098] The LED filament lamp 1; 100 may further comprise one or two electrically conductive base wires 14. In the embodiment shown in Fig. 3, the connection between the one or two electrically conductive base wires 14 and the electrically conductive wires of each LED filament 31-34 and 41-43 is achieved by means of a respective wire segment 15 connected to the one or two electrically conductive base wires 14 at a first end. The one or two electrically conductive base wires 14 penetrate the exhaust tube 12 to be electrically connected at a second end (not visible on the Figures) opposite to the first end to a driver 52 (cf. Fig. 6) or to the controller 5 or to a power source.

[0099] Turning finally to Fig. 6, an exemplary luminaire in the form of a pendant 50 is shown. The pendant 50 comprises a LED filament lamp 1; 100 according to any embodiment of the invention. In the embodiment shown, the LED filament lamp 1; 100 is of the type shown in Fig. 1 and comprises substantially straight filaments. The filaments of such a LED filament lamp 1; 100 may in other embodiments be filaments with another shape, such as, but not limited to, spiral-shaped, helix-shaped, meandering, twisted, flat and combinations thereof.

[0100] The pendant 50 further comprises a socket 51 for connecting the LED filament lamp 1; 100 to the pendant 50. The socket 51 is adapted to cooperate with the base 9 of the LED filament lamp 1; 100. The socket 51 may comprise a threading adapted to cooperate with the threading 10 of the LED filament lamp 1; 100. The socket 51 may comprise a terminal adapted to cooperate with the terminal 11 of the LED filament lamp 1; 100.

[0101] The pendant 50 may further comprise a driver 52 configured for controlling the LED filament lamp 1; 100. The driver 52 may or may not be the same unit as the controller 5 described above. In other words, the driver 52 and the controller 5 may be integrated into one and the same driver or controller, or they may be mutually separate units. The driver 52 is configured to power the plurality of LED filaments 31-34 and 41-43 via the electrically conducting wires of the LED filament lamp 1; 100. The driver 52 may further be configured for controlling at least one of the CCT of the LED filament lamp light 8 and the CRI of the LED filament lamp light 8. The driver 52 may also be configured for controlling other parameters related to the LED filament lamp light sources (that is, the plurality of LEDs), the first plurality of LED filaments 3, the first LED filament light 6, the second plurality of LED filaments 4, the second LED filament light 7, and the LED filament lamp light L3.

[0102] As shown in Fig. 6, the driver 52 is arranged on a reflector or screen 53 of the pendant 50. The driver may also be arranged within or incorporated into the reflector or screen 53. The pendant 50 further comprises an electrical wiring 54 for connection to a source of electricity, such as a mains.

[0103] It is noted that the pendant 50 shown in Fig. 6 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.

[0104] 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.

[0105] 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 LED filament lamp (1) configured to, in operation, provide LED filament lamp light (8), the LED filament lamp having a central lamp axis (CLA) and comprising: at least one first LED filament (3), each first LED filament (31-34) being an elongated element comprising a first length (LI) extending in a longitudinal direction (LD), a first width (Wl) extending perpendicular to the longitudinal direction (LD), a first thickness (Tl) extending perpendicular to the longitudinal direction (LD) and perpendicular to the first width (Wl), and a first aspect ratio (ARI), where ARI = Wl / Tl; and at least one second LED filament (4), each second LED filament (41-44) being an elongated element comprising a second length (L2) extending in a longitudinal direction (LD), a second width (W2) extending perpendicular to the longitudinal direction (LD), a second thickness (T2) extending perpendicular to the longitudinal direction (LD) and perpendicular to the second width (W2), and a second aspect ratio (AR2), where AR2 = W2 / T2; wherein each first LED filament is configured to, in operation, provide first LED filament light (6) with a first luminous flux (LF1); wherein each second LED filament is configured to, in operation, provide second LED filament light (7) with a second luminous flux (LF2); and wherein the second aspect ratio (AR2) is at least two times larger than the first aspect ratio (ARI).

2. A LED filament lamp according to claim 1, wherein one of the following applies:(i) the LED filament lamp comprises at least one first LED filament and a plurality of second LED filaments; and(ii) the LED filament lamp comprises at least one second LED filament and a plurality of first LED filaments.

3. A LED filament lamp according to claim 1 or 2, wherein the following applies:2 > ARI > 0.5;8 > AR2 > 2.5; and1.5 > T1 / T2 > 0.5.

4. A LED filament lamp according to any one of the preceding claims, wherein the following applies: the length ratio between the first length (LI) of each first LED filament (31- 34) and the second length (L2) of each second LED filament (41-43) is defined as L1 / L2, wherein 0.8 < L1 / L2 < 1.2; each of the first LED filaments (3) comprises a plurality of first LEDs and each of the second LED filaments (4) comprises a plurality of second LEDs, wherein the second plurality of LEDs comprises at least 1.5 more LEDs than the first plurality of LEDs; and the ratio between the first luminous flux (LF1) and the second luminous flux (LF2) is defined as LF1 / LF2, wherein LF1 / LF2 < 0.5.

5. A LED filament lamp according to any one of the preceding claims, wherein the at least one first LED filament (3) and the at least one second LED filament (4) are arranged along the central lamp axis (CLA), and alternatingly and evenly distributed around the central lamp axis (CLA).

6. A LED filament lamp according to any one of the preceding claims, wherein the at least one first LED filament (3) are arranged at a first distance (DI) from the central lamp axis (CLA) and the at least one second LED filament (4) are arranged at a second distance (D2) from the central lamp axis (CLA), and wherein DI > D2.

7. A LED filament lamp according to any one of the preceding claims, wherein spacings in a tangential direction between adjacent LED filaments is in a range of at least two times W1 and at most two times W2.

8. A LED filament lamp according to any one of the preceding claims, wherein each first LED filament (31-34) comprises a first plurality of LEDs(310) arranged on a first elongated carrier (311), wherein a first elongated encapsulant (312) is covering the first plurality of LEDs, the first elongated encapsulant comprises a firstluminescent material (313) configured to at least partly convert first LED light emitted by the first plurality of LEDs into first converted light and / or a first light scattering material (314) configured to at least partly scatter first LED light emitted by said first plurality of LEDs into first scattered light; wherein each second LED filament (41-43) comprises a second plurality of LEDs (410) arranged on a second elongated carrier (411), wherein a second elongated encapsulant (412) is covering the second plurality of LEDs, the second elongated encapsulant comprises a second luminescent material (413) configured to at least partly convert second LED light emitted by the second plurality of LEDs into second converted light and / or a second light scattering material (414) configured to at least partly scatter second LED light emitted by said second plurality of LEDs into second scattered light; and wherein (i) the thickness (TC2) of the second elongated carrier (411) is higher than the thickness (TCI) of the first elongated carrier (311) and / or (ii) the material of the second elongated carrier (411) has a higher thermal conductivity than the thermal conductivity of the material of the first elongated carrier (311).

9. A LED filament lamp according to claim 8, wherein the light transmissivity of the second elongated carrier (411) is lower than the light transmissivity of the first elongated carrier (311).

10. A LED filament lamp according to claim 8 or 9, wherein the first plurality of LEDs (310) are arranged in a first array having a single column and the second plurality of LEDs (410) are arranged in a second array having a plurality of columns.

11. A LED filament lamp according to any one of the preceding claims, wherein each first LED filament (31-34) comprises a first plurality of LEDs(310) arranged on a first elongated carrier (311), wherein a first elongated encapsulant (312) is covering the first plurality of LEDs, the first elongated encapsulant comprising a first luminescent material (313) configured to at least partly convert first LED light emitted by the first plurality of LEDs into first converted light; wherein each second LED filament (41-43) comprises a second plurality of LEDs (410) arranged on a second elongated carrier (411), wherein a second elongated encapsulant (412) is covering the second plurality of LEDs, the second elongated encapsulantcomprising a second luminescent material (413) configured to at least partly convert second LED light emitted by the second plurality of LEDs into second converted light; and wherein one or more of the following applies:(i) the thickness (TE1) of the first encapsulant (312) is lower than the thickness (TE2) of the second encapsulant ( 12), and(ii) the concentration of the first luminescent material (313) in the first encapsulant is lower than the concentration of the second luminescent material (413) in the second encapsulant, and(iii) the first luminescent material (313) is of a first type, Pl, and the second luminescent material (413) is of a second type, P2, where the second type, P2, is different from the first type, PL12. A LED filament lamp according to any one of the preceding claims, wherein each first LED filament (31-34) is configured to provide the first LED filament light (6) with a first correlated color temperature (CCT1) of less than or equal to 2500 K, and wherein each second LED filament (41-43) is configured to provide the second LED filament light (7) with a second correlated color temperature (CCT2) of more than or equal to 3000 K.

13. A LED filament lamp according to any one of the preceding claims, wherein the LED filament lamp (1) further comprises a controller (5), and wherein the controller is configured to operate the at least one first LED filament (3) and the at least one second LED filament (4) separately from one another.

14. A LED filament lamp according to claim 11, wherein the LED filament lamp (1) further comprises a controller (5), and wherein the controller further is configured to gradually change one or both of the first correlated color temperature (CCT1) and the second correlated color temperature (CCT2).

15. A luminaire comprising at least one LED filament lamp (1; 100) according to any one of the preceding claims.

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