LED lamp filament

Abstract

A light emitting diode, LED, filament (1) configured to emit, in operation, LED filament light (22), the LED filament (1) comprising an array of light emitting diodes (2), LEDs, the array comprising a plurality of LEDs (20) configured to emit, in operation, LED light (23); a circuit arrangement (19) coupled to the plurality of LEDs (20); an elongated carrier (3), the plurality of LEDs (20) being arranged on a first main surface (31) of the elongated carrier (3); an encapsulant (5) comprising a translucent material, the encapsulant (5) at least partially surrounding the plurality of LEDs (20) and the elongate carrier (3); and an at least partially reflective layer (4) configured to be perceived by an observer as golden, configured to at least partially transmit and at least partially reflect one or more of the LED light (23), and arranged at least on the same side of the elongate carrier (3) as the plurality of LEDs (20).

Description

Technical Field

[0001] The present invention relates to a light emitting diode (LED) filament, which is configured to emit LED filament light in an emission direction during operation. The LED filament comprises an array of light emitting diodes (LED), the array comprising a plurality of LEDs, the plurality of LEDs being configured to emit LED light during operation; a circuit device coupled to the plurality of LEDs; an elongated carrier, the plurality of LEDs being arranged on a surface of the elongated carrier; and an encapsulant comprising a translucent material, the encapsulant at least partially surrounding the plurality of LEDs and the elongated carrier.

[0002] As used herein, the terms carrier and elongated carrier may be used interchangeably such that the elongated carrier may also be simply denoted as a carrier. Background Art

[0003] The current trend in lighting is to use LED filament lamps. An LED filament lamp is an LED lamp that includes an LED filament and, for aesthetic and light distribution purposes, is designed to resemble a traditional incandescent light bulb with a visible filament, but with the high efficiency of a light emitting diode.

[0004] The LED filament provides 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 a non-straight configuration, such as a curved configuration, a 2D / 3D spiral or a helix. Preferably, the LEDs are arranged on an elongated carrier, such as a carrier, which may be rigid (made of, for example, a polymer, glass, quartz, metal or sapphire) or flexible (made of, for example, a polymer or metal, such as a film or foil).

[0005] In case the carrier comprises a first main surface and an opposing second main surface, the LEDs are arranged on at least one of these surfaces.The carrier may be reflective or light transmissive, such as translucent, preferably transparent.

[0006] The LED filament may include an encapsulant that at least partially covers at least a portion of the plurality of LEDs. The encapsulant may also at least partially cover at least one of the first major surface and the second major surface. The encapsulant may be a flexible polymer material, such as silicone. In addition, the LED may be arranged to emit, for example, LED light of different colors or spectra. The encapsulant may include a luminescent material that is configured to at least partially convert the LED light into converted light. The luminescent material may be a phosphor, such as an inorganic phosphor and / or quantum dots or quantum dot rods. The phosphor may include a first phosphor that provides green / yellow light and / or a second phosphor that provides red light. The first phosphor may include YAG and / or LuAG. The second phosphor may include a KSiF phosphor.

[0007] An LED filament may include multiple sub-filaments.

[0008] CN203892915U discloses a linear LED light emitting device, which includes an LED light source arranged on a transparent carrier made of glass. The carrier is provided with a transparent fluorescent phosphor layer encapsulating the LED light source and a transparent fluorescent phosphor layer on a side opposite to the LED light source. A reflective layer is provided on each side surface of the carrier and thus extends between the two phosphor layers. The reflective reflective layer is a reflective coating comprising at least one metal selected from gold, silver, aluminum, copper, nickel, iron and tin.

[0009] CN205606240U discloses an LED lamp, which comprises a bulb and an LED filament in the bulb. The LED filament comprises a metal carrier, and a gold coating material is arranged on the top of the metal carrier.

[0010] It would be desirable to provide an LED filament that provides improved decorative lighting and / or has an improved appearance (while still being efficient).

[0011] There is also a need to provide such an LED filament, which is simple and inexpensive to manufacture. Summary of the invention

[0012] It is therefore an aspect of the present invention to provide an alternative LED filament which preferably further at least partially obviates (one or more of) one or more of the above disadvantages. It is an object of the present invention to overcome or ameliorate at least one disadvantage of the prior art, or to provide a useful alternative. It may be an object of the present invention to provide an LED filament which provides improved decorative lighting and / or has an improved appearance (while still being efficient). It is an object of the present invention to provide such an LED filament which is simple and inexpensive to manufacture.

[0013] According to a first aspect of the invention, this and other objects are achieved by means of a light emitting diode, an LED filament, the LED filament being configured to emit LED filament light during operation, the LED filament comprising an array of light emitting diodes LED, the array comprising a plurality of LEDs, the plurality of LEDs being configured to emit LED light during operation; a circuit device coupled to the plurality of LEDs; an elongated carrier, the plurality of LEDs being arranged on a first main surface of the elongated carrier; an encapsulation comprising a translucent material, the encapsulation at least partially surrounding the plurality of LEDs and the elongated carrier, and an at least partially reflective layer, the at least partially reflective layer being configured to be perceived as gold by an observer, the at least partially reflective layer being configured to at least partially transmit and at least partially reflect the LED light, and the at least partially reflective layer being arranged at least on the same side of the elongated carrier as the plurality of LEDs.

[0014] Thereby, in particular by providing an at least partially reflective layer configured to be perceived as a golden colour by an observer, configured to at least partially transmit and at least partially reflect LED light, and arranged at least on the same side of the elongated carrier as the plurality of LEDs, an LED filament is provided, with which the decorative lighting and appearance of the LED filament is improved while still being efficient.

[0015] Furthermore, by providing at least a portion of the reflective layer configured to be perceived as golden by an observer and arranged on the same side of the elongated carrier as the plurality of LEDs, an LED filament is provided which has a golden appearance both in an on state and in an off state, that is, regardless of whether the plurality of LEDs are emitting LED light or not.

[0016] This type of LED filament also has a very simple structure and can be produced at a low cost.

[0017] In one embodiment, at least 60% of the LED light is transmitted through the at least partially reflective layer, more preferably at least 70% of the LED light is transmittable through the at least partially reflective layer, and most preferably at least 80% of the LED light is transmittable through the at least partially reflective layer.

[0018] In an embodiment, at least part of the reflective layer may have a metallic appearance.

[0019] In an embodiment, at least part of the reflective layer may include a metal. The metal may include gold and / or copper. The metal may be an alloy.

[0020] In an embodiment, the at least partially reflective layer may have an (average) transmittance in the range of 30% to 70%, preferably in the range of 35% to 65%, more preferably in the range of 38% to 62%, most preferably in the range of 40% to 60%.

[0021] In an embodiment, the at least partially reflective layer may have a (average) reflectance in the range of 30% to 70%, preferably in the range of 35% to 65%, more preferably in the range of 38% to 62%, most preferably in the range of 40% to 60%.

[0022] Thus, the above advantages can be obtained without compromising the overall light output of the LED filament, ie the quality and intensity of the LED filament light. This is particularly useful in embodiments where at least a partially reflective layer is arranged over the plurality of LEDs, such as on the LEDs or on the encapsulant.

[0023] In one embodiment, at least a portion of the reflective layer is configured to be non-conductive or electrically isolated.

[0024] Thereby, it is ensured that the at least partially reflective layer does not interfere with the functionality of any electrical components of the LED filament, such as circuitry. This in turn provides a safer LED filament.

[0025] In one embodiment, the LED filament has an LED filament periphery, and at least 80% of the LED filament periphery is at least partially covered by the reflective layer, preferably, at least 85% of the LED filament periphery can be covered by at least partially the reflective layer, more preferably, at least 90% of the LED filament periphery can be covered by at least partially the reflective layer, and most preferably, at least 95% of the LED filament periphery can be covered by at least partially the reflective layer.

[0026] Thereby, the LED filament is configured to be perceived by an observer as golden in a particularly uniform manner.

[0027] In one embodiment, the package further comprises a luminescent material configured to at least partially convert the LED light into converted light, wherein the at least partially reflective layer is configured to at least partially transmit and at least partially reflect at least one of the converted light, preferably, at least 60% of the converted light can be transmitted through the at least partially reflective layer, more preferably, at least 70% of the converted light can be transmitted through the at least partially reflective layer, preferably, at least 80% of the converted light can be transmitted through the at least partially reflective layer.

[0028] Hereby, an LED filament is obtained which provides a light output with improved quality and with which the filament-like appearance remains visible.

[0029] The term "luminescent material" in this context particularly relates to inorganic luminescent materials. Luminescent materials may also be referred to as phosphors. These terms are known to the person skilled in the art.

[0030] In an embodiment, quantum dots can be used as luminescent materials and can be optionally embedded in a transmission matrix, such as a polymer, such as PMMA, or polysiloxane, etc. Quantum dots are small crystals of semiconductor materials, and their width or diameter is generally only a few nanometers. When excited by incident light, the color of the light emitted by the quantum dots is determined by the size and material of the crystal. Therefore, light of a specific color can be produced by adjusting the size of the dots. Most known quantum dots that emit in the visible light range are based on cadmium selenide (CdSe), which has shells such as cadmium sulfide (CdS) and zinc sulfide (ZnS). Quantum dots without cadmium, such as indium phosphide (InP) and copper indium sulfide (CuInS2) and / or silver indium sulfide (AgInS2) can also be used. Quantum dots show very narrow emission bands, and therefore they show saturated colors. In addition, the emission color can be easily adjusted by adjusting the size of the quantum dots. Any type of quantum dots known in the art can be used in the present invention. However, for environmental safety and consideration reasons, it is preferred to use cadmium-free quantum dots or at least quantum dots with very low cadmium content. Instead of or in addition to quantum dots, other quantum confinement structures may also be used. In the context of this application, the term "quantum confinement structures" is to be understood as meaning, for example, quantum wells, quantum dots, quantum rods, tripods, tetrapods or nanowires.

[0031] In particular, the luminescent material is configured to convert at least part of the LED light into luminescent material light having an emission band having a wavelength in one or more of (a) a green spectral wavelength range and (b) a yellow spectral wavelength range, wherein the luminescent material comprises a (garnet) luminescent material of the A3B5O12:Ce type, wherein A comprises one or more of Y, La, Gd, Tb and Lu, and wherein B comprises one or more of Al, Ga, In and Sc. Thus, the luminescent material light may be, for example, green or yellow (or even orange in a particular embodiment (depending on the composition of the garnet and the cerium concentration)). However, other embodiments are also possible, see below. In an embodiment, 0.05-10% of the A element comprises Ce, even more particularly 0.05-5%, such as 0.1-5%. In particular, in an embodiment, 0.1-3% of the A element comprises Ce, such as up to 2%, such as selected from the range of 0.1-1.5%, such as at least higher than 0.5%.

[0032] Alternatively or additionally, the luminescent material may be, for example, M2Si5N8:Eu2+ and / or MAlSiN3:Eu2+ and / or Ca2AlSi3O2N5:Eu2+, etc. In a specific embodiment, the first luminescent material may include one or more materials selected from the group consisting of (Ba, Sr, Ca)S:Eu, (Ba, Sr, Ca)AlSiN3:Eu and (Ba, Sr, Ca)2Si5N8:Eu. In these compounds, europium (Eu) is substantially or only divalent and replaces one or more specified divalent cations. In general, Eu will not be present in an amount greater than 10% of the cation; its presence is particularly in the range of about 0.5 to 10%, more particularly in the range of about 0.5 to 5%, relative to the cation (one or more) it replaces. The term ":Eu" indicates that part of the metal ion is replaced by Eu (in these examples by Eu2+). For example, assuming that there is 2% Eu in CaAlSiN3:Eu, the correct formula should be (Ca0.98Eu0.02)AlSiN3.

[0033] In one embodiment, the package does not have a luminescent material, and the package includes a light scattering material, which is configured to at least partially scatter the LED light into scattered light, wherein the at least partially reflective layer is configured to at least partially transmit and at least partially reflect at least one of the scattered light, preferably, at least 60% of the scattered light can be transmitted through the at least partially reflective layer, preferably, at least 70% of the scattered light can be transmitted through the at least partially reflective layer, preferably, at least 80% of the scattered light can be transmitted through the at least partially reflective layer.

[0034] Thereby, an LED filament is provided which has a particularly directionally uniform light output.

[0035] In one embodiment, an at least partially reflective layer is provided on the encapsulant.

[0036] Thereby, an LED filament is provided which has a very simple structure and is also easy to produce.

[0037] In one embodiment, the at least partially reflective layer is provided as a reflective coating on the plurality of LEDs.

[0038] Thereby, an LED filament with a very simple structure is provided.

[0039] In an embodiment, the at least partially reflecting layer is provided on the surface of the elongated carrier, covering at least 60% of the carrier, on which the plurality of LEDs are arranged, preferably at least 70% of the carrier, more preferably at least 80% of the carrier, most preferably at least 90% of the carrier.

[0040] Thus, an LED filament is provided which is very simple in structure and very simple in manufacture.

[0041] In one embodiment, at least part of the reflective layer is provided on the same side of the elongated carrier as the plurality of LEDs and between the elongated carrier and the electrically insulating reflective layer.

[0042] Thereby, it is ensured that at least part of the reflective layer is electrically insulated from any electrical components of the LED filament, such as circuitry. This in turn provides a safer LED filament.

[0043] In an embodiment, an at least partially reflecting layer is provided on the carrier, around the plurality of LEDs, covering at least 60% of the carrier, preferably at least 70% of the carrier, more preferably at least 80% of the carrier, most preferably at least 90% of the carrier.

[0044] This provides an LED filament of particularly simple construction.

[0045] In one embodiment, the at least partially reflecting layer is provided on the encapsulation, or as a foil or tube arranged around the encapsulation.In particular, the foil or tube may be attached, such as glued, to the encapsulation of the LED filament.

[0046] Thereby, an LED filament is provided which is particularly easy and simple to produce.

[0047] In one embodiment, the elongated carrier is a transparent elongated carrier, and the at least partially reflective layer is arranged on a side of the elongated carrier opposite to the plurality of LEDs. More specifically, the at least partially reflective layer is provided on a side or second major surface of the elongated carrier, the side or second major surface extending opposite and parallel to a first major surface of the elongated carrier, on which the LED filament light source is arranged.

[0048] Thereby, the LED filament is configured to be perceived by an observer as golden in a particularly uniform manner.

[0049] In one embodiment, the at least partially reflective layer includes a reflectivity of 30%-40% for light with a wavelength less than 490nm, a reflectivity of greater than 80% for light with a wavelength greater than 600nm, and a reflectivity that gradually increases with wavelength for light with a wavelength between 490nm and 600nm.

[0050] Such a combination of light wavelength-dependent reflectivities has been shown to provide a particularly golden appearance, ie an appearance very similar to gold.

[0051] In one embodiment, the surface of the LED filament comprises less than 30% reflectance.

[0052] This can be obtained by providing the encapsulation without luminescent material and comprising a suitably low concentration of light scattering material.Thereby, the light quality is improved.

[0053] In one embodiment, at least 70% of the first major surface of the elongated carrier is covered by the at least partially reflecting layer.

[0054] Thereby, the LED filament is configured to be perceived as a golden color by an observer in a sufficiently uniform manner.

[0055] In one embodiment, the at least partially reflective layer is provided with a total reflectivity in the range of 20% to 60%.

[0056] Such a total reflectivity of the at least partially reflecting layer has been shown to provide a particularly golden appearance, ie an appearance very similar to gold.

[0057] In one embodiment, the at least partially reflective layer is provided as particles or flakes in a polymer binder or a transparent polymer binder or silicone.

[0058] Since polymer binders, transparent polymer binders and in particular silicones are able to withstand high intensities of light and heat, this provides a particularly durable LED filament.

[0059] In one embodiment, at least part of the reflective layer is provided using vapour deposition.

[0060] Thereby, an at least partially reflecting layer can be provided in a particularly simple and straightforward manner.

[0061] Phosphors of this type have proven to be particularly well functionalized when a golden appearance is desired.

[0062] In one embodiment, parts of the elongated carrier are not covered by the encapsulation to ensure that at least a part of the at least partially reflective layer is free of the encapsulation.

[0063] Thereby, an LED filament is provided which has an improved filamentary appearance in a structurally simple manner due to the perceived difference between the portions of the at least partially reflecting layer respectively covered by the encapsulation and the portions of the at least partially reflecting layer not provided with the encapsulation.

[0064] In one embodiment, at least 40% of the surface area of ​​the at least partially reflective layer is free of encapsulant.

[0065] As a result, an LED filament is provided which has a particularly good filament-like appearance in a structurally simple manner.

[0066] In one embodiment, the elongate carrier is curved.

[0067] When the surface of such a curved elongated carrier is provided with an at least partially reflecting layer, an LED filament with a quantitatively improved reflection is obtained and which provides LED filament light with an improved brightness.

[0068] In one embodiment, the LED filament further comprises an additional array of light emitting diodes LEDs, the additional array comprising an additional plurality of LEDs configured to emit additional LED light in operation, and an additional circuit arrangement coupled to the additional plurality of LEDs, the additional plurality of LEDs being arranged on a second surface of the elongated carrier opposite to the first main surface, and an additional at least partially reflective layer, the additional at least partially reflective layer being configured to be perceived as a golden color by an observer, the additional at least partially reflective layer being configured to at least partially transmit and at least partially reflect one or more of the additional LED light, and the additional at least partially reflective layer being arranged at least on the same side of the elongated carrier as the additional plurality of LEDs.

[0069] Thus, an LED filament is provided with which the decorative lighting and appearance of the LED filament, in particular the golden color in both the on and off states, is improved, while still being efficient regardless of the viewing angle and applicable to multiple LEDs.

[0070] This type of LED filament can also provide light output with higher intensity, and also has a very simple structure and low production cost.

[0071] In one embodiment, the further at least partially reflective layer is configured to at least partially transmit and at least partially reflect the further LED light.

[0072] In one embodiment, the further at least partially reflective layer is configured to be non-conductive or electrically isolated.

[0073] In one embodiment, the LED filament has an LED filament circumference, wherein at least 80% of the LED filament circumference is covered by the at least partially reflecting layer and the further at least partially reflecting layer in total.

[0074] In one embodiment, the LED filament comprises a further encapsulant encapsulating a further LED filament light source.

[0075] In further embodiments, the further encapsulant comprises a translucent material and the further encapsulant at least partially surrounds the further plurality of LEDs and the elongated carrier.

[0076] The package and the further package may be identical or different from each other.

[0077] In further embodiments, the further encapsulant comprises a luminescent material configured to at least partially convert the further LED light into converted further light, and the further at least partially reflective layer is configured to at least partially transmit and at least partially reflect the converted further light.

[0078] In further embodiments, the further package does not have luminescent material and the further package includes a light scattering material configured to at least partially scatter the further LED light into further scattered light, wherein the further at least partially reflective layer is configured to at least partially transmit and at least partially reflect at least one of the further scattered light.

[0079] In one embodiment, the further at least partially reflective layer is provided as a reflective coating as any one or more of the following: on the further plurality of LEDs, on a surface of an elongated carrier, on a surface on which the further plurality of LEDs are arranged, on the same side of the elongated carrier as the further plurality of LEDs and below the electrically insulating reflective layer, on the elongated carrier around the further plurality of LEDs, and on or as a foil arranged around a further encapsulation.

[0080] In an embodiment, parts of the elongated carrier are not covered by the further encapsulation, thereby ensuring that at least a part of the further at least partially reflecting layer is free of the further encapsulation.

[0081] In an embodiment, the at least partially reflecting layer is arranged on the light emitting device in such a way that at least a part or the whole of the at least partially reflecting layer extends parallel to a surface of the elongated carrier, on which surface the plurality of LEDs are arranged.

[0082] In an embodiment the further at least partially reflecting layer is arranged on the light emitting device in such a way that at least a part or all of the further at least partially reflecting layer extends parallel to a surface of the elongated carrier on which the further plurality of LEDs are arranged.

[0083] In an embodiment, the LED filament light may be white light. The white light may have a correlated color temperature (CCT) in the range of 1800 to 5000K, preferably in the range of 1800 to 4000K, more preferably in the range of 1800 to 3000K, most preferably in the range of 1800 to 2500K, which is the desired CCT range for LED filaments. The white light may have a color rendering index (CRI) of at least 80, preferably at least 85, more preferably at least 88, and most preferably at least 90.

[0084] In embodiments, the at least partially reflective layer may be a layer and / or a coating.

[0085] In an embodiment, the LED filament may have a length L, a width W and a height H, wherein L ≥ 10 W and / or L ≥ 10 H. In particular, L may be in the range of 3 to 10 cm, W may be in the range of 1 to 10 mm, and / or H may be in the range of 1 to 10 mm.

[0086] In an embodiment, the second main surface may include a further encapsulant. In particular, the further encapsulant may include a further luminescent material and / or a further light scattering material. In particular, the at least partially reflective layer may be arranged on the further encapsulant.

[0087] The invention also relates to a lamp or a light, comprising an LED filament according to the invention.

[0088] In one embodiment, such a lamp is an LED filament lamp comprising at least one LED filament according to the invention and a driver configured to supply power to a plurality of LEDs via the circuit arrangement of the LED filament.

[0089] In one embodiment, the LED filament lamp may further include a base for electrically and mechanically connecting the LED filament lamp to a socket of a lamp.

[0090] In embodiments, the lamp or luminaire may further include one or more of a controller, an antenna, and an enclosure at least partially enclosing the LED filament.

[0091] It is noted that the invention relates to all possible combinations of features recited in the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0092] This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiments of the invention.

[0093] Figure 1 A cross-sectional view of an LED filament according to a first embodiment of the present invention is shown.

[0094] Figure 2 A cross-sectional view of an LED filament according to a second embodiment of the present invention is shown.

[0095] Figure 3 A cross-sectional view of an LED filament according to a third embodiment of the present invention is shown.

[0096] Figure 4 A cross-sectional view of an LED filament according to a fourth embodiment of the present invention is shown.

[0097] Figure 5 A top view of an LED filament light source according to the invention is shown, the light source comprising a plurality of LEDs arranged on an elongated carrier provided with a reflective layer, the encapsulation being omitted.

[0098] Figure 6 A cross-sectional view of an LED filament according to a fifth embodiment of the present invention is shown.

[0099] Figure 7 A cross-sectional view of an LED filament according to a sixth embodiment of the present invention is shown.

[0100] Figure 8 A cross-sectional view of an LED filament according to a seventh embodiment of the present invention is shown.

[0101] Fig. 9 A cross-sectional view of an LED filament according to an eighth embodiment of the present invention is shown.

[0102] Fig.10 A cross-sectional view of an LED filament according to a ninth embodiment of the present invention is shown.

[0103] Fig.11 A graph showing the reflectance of a reflective layer of an LED filament according to the invention as a function of the wavelength of light incident on the at least partially reflective layer.

[0104] Fig.12 A cross-sectional view of a lamp comprising an LED filament according to the invention is shown.

[0105] As shown in the figures, the size of the reflective layers and regions are exaggerated for illustrative purposes and, therefore, are provided to illustrate the general structure of an embodiment of the present invention. Like reference numerals refer to like elements throughout. DETAILED DESCRIPTION

[0106] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the present invention are shown. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; on the contrary, these embodiments are provided to be thorough and complete and to fully convey the scope of the present invention to the skilled person.

[0107] Figure 1 A cross-sectional view of an LED filament 1 according to a first embodiment of the invention is shown. In general, regardless of the embodiment, the LED filament 1 comprises an array of light emitting diodes, an LED 2 , a carrier 3 , an at least partially reflective layer 4 , an encapsulation 5 and a circuit arrangement 19 .

[0108] The at least one LED filament 1 is configured to emit LED filament light 22 in operation. The LED filament light 22 may be light of any suitable color, such as white light. The light of the LED filament 22 may include one or more of LED light, converted light, and scattered light. The LED filament light 22 is emitted in an emission direction D. Also refer to Figure 5 , at least one LED filament 1 comprises an array of LEDs 2, the array of LEDs 2 comprising a plurality of LEDs 20. The plurality of LEDs 20 are configured to emit LED light 23. The LEDs 20 may be any suitable type of LED, such as a white LED or a combination of red, green and blue LEDs. The plurality of LEDs 20 may comprise at least 5 LEDs, preferably at least 10 LEDs, more preferably at least 15 LEDs, and most preferably at least 20 LEDs.

[0109] The plurality of LEDs 20 of the array of LEDs 2 of the LED filament 1 are arranged on a surface 31 of a carrier 3. The surface 31 is a first main surface 31 of the carrier 3. The carrier 3 is an elongated carrier 3. The elongated carrier 3 may be a substrate. The elongated carrier 3 or substrate may be a printed circuit board (PCB).

[0110] The circuit arrangement 19 is coupled to the plurality of LEDs 20 to provide electrical energy to the plurality of LEDs 20. The circuit arrangement 19 is separated from the at least partially reflective layer 4. The circuit arrangement 19 may be arranged on or in the elongated carrier 3. The circuit arrangement 19 may comprise at least one first electrical track and at least one second electrical track.

[0111] The encapsulant 5 at least partially surrounds the plurality of LEDs 20 and the elongated carrier 3. The encapsulant 5 comprises a translucent material. The translucent material of the encapsulant 5 may be a polymer such as silicone that can withstand high intensity light and heat.

[0112] Regardless of the embodiment, the at least partially reflective layer 4 is generally configured to be perceived as a gold color by an observer. The at least partially reflective layer 4 is partially transmissive or partially reflective or both for the LED light 23. The at least partially reflective layer 4 is configured to direct the light away from the array 2 of LEDs. The at least partially reflective layer 4 is arranged at least on or near the same side 31 of the elongated carrier 3 as the plurality of LEDs 20. The LED filament 1 has an LED filament periphery. At least 80% of the LED filament periphery may be covered by the at least partially reflective layer 4.

[0113] The at least partially reflective layer 4 has a reflectivity of 30%-40% for light with a wavelength less than 490nm (i.e., blue light). The at least partially reflective layer 4 has a reflectivity of more than 80% for light with a wavelength greater than 600nm (i.e., red light). In addition, for light with a wavelength between 490nm and 600nm, i.e., for green light and yellow light, the at least partially reflective layer 4 includes a reflectivity that gradually increases with wavelength. This is achieved by Fig.11The example in the graph of is shown, showing the reflectance R of the at least partially reflective layer 4 as a function of the wavelength of light incident on the at least partially reflective layer 4. The at least partially reflective layer 4 does not have a luminescent material. That is, the at least partially reflective layer 4 does not include any luminescent material. The at least partially reflective layer 4 also includes a back reflection of less than 30%.

[0114] The at least partially reflective layer 4 may be non-conductive. That is, the at least partially reflective layer 4 may be configured to be non-conductive. The at least partially reflective layer 4 may be electrically insulating. The at least partially reflective layer 4 may be provided as particles or fragments in a polymer binder or a transparent polymer binder or silicone. The at least partially reflective layer 4 may be provided by using a vapor deposition process.

[0115] exist Figure 1 In the embodiment shown, the at least partially reflective layer 4 is provided on the encapsulant 5. For example, the at least partially reflective layer 4 can be provided as a foil arranged around the encapsulant 5 or as a coating on the encapsulant 5. 70% or more of the surface of the encapsulant 5 is covered by the at least partially reflective layer 4.

[0116] Figure 2 FIG. 1 shows a cross-sectional view of an LED filament 100 according to a second embodiment of the present invention. The LED filament 100 differs from the above-mentioned LED filaments due to the following features: Figure 1 Description of LED filament 1.

[0117] An at least partially reflective layer 4 is provided on the elongated carrier 3, below or underneath the array of LEDs 2, and also below or underneath an electrically insulating reflective layer 6. In this embodiment, the encapsulation 5 may in principle be omitted.

[0118] However, Figure 2 The LED filament 100 is shown to include an encapsulant 5. The encapsulant 5 also includes a luminescent material configured to at least partially convert the LED light 22 into converted light 24. The at least partially reflective layer 4 is also configured to at least partially transmit and / or at least partially reflect the converted light 24.

[0119] Figure 3 FIG. 1 shows a cross-sectional view of an LED filament 101 according to a third embodiment of the present invention. The LED filament 101 differs from the above embodiments of the present invention due to the following features: Figure 1 to Figure 2 Description of LED filament.

[0120] An at least partially reflective layer 4 is provided on a surface 31 of the elongated carrier 3 on both sides of the LEDs 20 of the array of LEDs 2 .

[0121] In this embodiment, the encapsulant 5 does not have a luminescent material. The encapsulant 5 also includes a light scattering material 26 configured to at least partially scatter the LED light 22 into scattered light 25. In such embodiments, the at least partially reflective layer 4 can be configured to at least partially transmit and / or at least partially reflect the scattered light 25. The light scattering material 26 is Figure 3 In the figure, scattering particles are shown, but they can also be, for example, a coating on the encapsulation 5 or incorporated into the encapsulation 5.

[0122] Figure 4 FIG. 1 shows a cross-sectional view of an LED filament 102 according to a fourth embodiment of the present invention. The LED filament 102 differs from the above embodiments due to the following features: Figures 1 to 3 Description of LED filament.

[0123] At least part of the reflective layer 4 is similar to the above reference Figure 1 The embodiment described is provided on the encapsulant 5. A further reflective layer 8 is provided on a further surface 32 of the elongated carrier 3, which is opposite to the surface 31 on which the array of LEDs 2 is arranged. The further surface 32 is a second main surface 32 extending opposite to the first main surface 31. The further at least partially reflective layer 8 is identical or similar to the at least partially reflective layer 4. Figure 4 In some embodiments of the type shown, the at least partially reflecting layer 4 provided on the encapsulant 5 may be omitted.

[0124] Regardless of the embodiment, the further at least partially reflective layer 8 is generally configured to be perceived as a golden color by an observer. The further at least partially reflective layer 8 is partially transmissive or partially reflective or both for the LED light. The further at least partially reflective layer 8 is configured to direct light away from the array of LEDs 2.

[0125] The additional at least partially reflective layer 8 has a reflectivity of 30%-40% for light with a wavelength less than 490nm (i.e., blue light). The additional at least partially reflective layer 8 has a reflectivity greater than 80% for light with a wavelength greater than 600nm (i.e., red light). In addition, the additional at least partially reflective layer 8 includes a reflectivity that gradually increases with the wavelength of light with a wavelength between 490nm and 600nm (i.e., green light and yellow light). The additional at least partially reflective layer 8 does not have a luminescent material. That is, the additional at least partially reflective layer 8 does not include any luminescent material. The additional at least partially reflective layer 8 also includes a back reflection of less than 30%.

[0126] The further at least partially reflecting layer 8 may be non-conductive.The further at least partially reflecting layer 8 may be provided as particles or fragments in a polymer binder or a transparent polymer binder or silicone.The further at least partially reflecting layer 8 may be provided by using a vapour deposition process.

[0127] Figure 6 FIG. 1 shows a cross-sectional view of an LED filament 103 according to a fifth embodiment of the present invention. The LED filament 103 differs from the above embodiments of the present invention due to the following features: Figures 1 to 4 Description of LED filament.

[0128] The LED filament 103 comprises a further array of LEDs 7. The further array of LEDs 7 comprises a further plurality of LEDs configured to emit further LED light in operation. The further array of LEDs 7 is arranged on a further surface 32 of the elongated carrier 3. In the embodiment shown, the further surface 32 extends opposite and parallel to the surface 31 on which the array of LEDs 2 is arranged. The further circuit arrangement 21 is coupled to the further plurality of LEDs in order to provide electrical energy to the further plurality of LEDs. The further circuit arrangement 21 is separated from the at least partially reflective layer 4. The further circuit arrangement 21 may be arranged on or in the elongated carrier 3.

[0129] The LED filament 103 comprises a further reflective layer 8 which is configured to be perceived as a golden color by an observer. The further at least partially reflective layer 8 is partially transmissive or partially reflective or both for the further LED light. The further at least partially reflective layer 8 is configured to direct light away from the further array of LEDs 7.

[0130] A further at least partially reflective layer 8 is provided on the elongate carrier 3, beneath or below the further array of LEDs 7, and also beneath or below the further electrically insulating reflective layer 10. In other embodiments, the electrically insulating reflective layer 10 may be omitted.

[0131] The LED filament 103 further comprises a further encapsulant 9 which at least partially surrounds the further array of LEDs 7 and the elongated carrier 3. The further encapsulant 9 comprises a translucent material. The translucent material of the further encapsulant 9 may be a polymer such as silicone capable of withstanding high intensity light and heat.

[0132] However, in some embodiments, the further encapsulation 9 can in principle be omitted.

[0133] Figure 7 FIG. 1 shows a cross-sectional view of an LED filament 104 according to a sixth embodiment of the present invention. The LED filament 104 is very similar to Figure 6 The LED filament 103 is shown, but differs due to the following features.

[0134] A further at least partially reflective layer 8 is provided on the surface 32 of the elongate carrier 3 on both sides of the further array of LEDs 7 .

[0135] The other packaging material 9 can be the same as the above reference Figures 1 to 4 Any type of encapsulation 5 described is similar or identical. The further encapsulation 9 and the encapsulation 5 may be identical. The further encapsulation 9 and the encapsulation 5 may be integral. Alternatively, the further encapsulation 9 and the encapsulation 5 may be different from each other.

[0136] For example, the further encapsulant 9 may comprise a luminescent material configured to at least partially convert the further LED light into converted further light.The further at least partially reflecting layer 8 may then also be configured to at least partially transmit and / or at least partially reflect the converted further light.

[0137] Alternatively, the further encapsulant 9 may not have luminescent material. The further encapsulant 9 may then include a light scattering material configured to at least partially scatter the further LED light into further scattered light. In such an embodiment, the further at least partially reflective layer 8 may then be configured to at least partially transmit and / or at least partially reflect the further scattered light. The light scattering material of the further encapsulant 9 may be, for example, scattering particles or a coating on the further encapsulant 9.

[0138] Figure 8 FIG. 1 shows a cross-sectional view of an LED filament 105 according to a seventh embodiment of the present invention. The LED filament 105 differs from the above embodiments due to the following features: Figures 1 to 4 and 6 to Figure 7 Description of LED filament.

[0139] The encapsulation 5 covers only part of the surface 31 of the elongated carrier 3 and thus only part of the at least partially reflecting layer 4. In other words, at least a portion 11 of the at least partially reflecting layer 4 is not provided with the encapsulation 5. For example, at least 30%, at least 40% or at least 50% of the surface area of ​​the at least partially reflecting layer 4 may be free of the encapsulation 5.

[0140] If the lighting device comprises a further encapsulation 9, see for example Figure 6 and 7 Embodiments are also possible, wherein the further encapsulant 9 covers only part of the surface 32 of the elongated carrier 3 and thus only part of the further at least partially reflecting layer 8. In other words, at least a part of the further at least partially reflecting layer 8 may be free of the further encapsulant 9. For example, at least 30%, at least 40% or at least 50% of the surface area of ​​the further at least partially reflecting layer 8 may be free of the further encapsulant 9.

[0141] Fig. 9FIG. 1 shows a cross-sectional view of an LED filament 106 according to an eighth embodiment of the present invention. The LED filament 106 differs from the above embodiments due to the following features: Figures 1 to 4 and Figures 6 to 8 Description of LED filament.

[0142] The elongated carrier 3 is a curved elongated carrier. The array of LEDs 2, the at least partially reflecting layer 4 and the encapsulation 5 (if provided) are arranged on a concave surface 31 of the elongated carrier 3. Thus, the curved elongated carrier 3 with the at least partially reflecting layer 4 acts as a more efficient reflector. The curved elongated carrier may also be convex or a combination of concave and convex.

[0143] Fig.10 FIG. 1 shows a cross-sectional view of an LED filament 107 according to a ninth embodiment of the present invention. The LED filament 107 differs from the above embodiments due to the following features: Figures 1 to 4 and Figures 6 to 9 Description of LED filament.

[0144] The elongated carrier 3 is generally provided with a plurality of surfaces 31 and on each of the surfaces 31 an array of LEDs 2 and a reflective layer 4 is provided. Hereby, a still further improved reflection is obtained. Fig.10 In the exemplary embodiment shown, the elongated carrier comprises four surfaces 31a, 31b, 31c, 31d. On each of the surfaces 31a, 31b, 31c, 31d, an array of LEDs 2a, 2b, 2c and 2d, and a reflective layer 4a, 4b, 4c and 4d are arranged respectively. The respective array of LEDs 2a, 2b, 2c and 2d comprises a plurality of LEDs. The circuit arrangement 19a, 19b, 19c, 19d is coupled to the respective plurality of LEDs, respectively, so as to provide electrical energy for the respective plurality of LEDs. The circuit arrangement 19a, 19b, 19c, 19d is separated from the respective at least partially reflective layer 4a, 4b, 4c, 4d. The circuit arrangement 19a, 19b, 19c, 19d can be arranged on or in the elongated carrier 3.

[0145] Fig.12 An exemplary lamp 12 is shown including an LED filament 1 according to any embodiment of the present invention. In the embodiment shown, the LED filament 1 is a substantially straight LED filament. In other embodiments, the LED filament 1 of such a lamp may be an LED filament having other shapes, such as but not limited to spiral, helical, meandering, twisted, flat, and combinations thereof.

[0146] The lamp 12 further includes a driver or controller 17 configured to control the LED filament light source of the LED filament 1. The controller 17 is configured to supply power to the plurality of LEDs 20 via the circuit arrangement 21 of the LED filament 1. The controller 17 may also be configured to control at least one of the CCT of the LED filament light source light and the CRI of the LED filament light source light. The controller 17 may also be configured to control other parameters related to the LED filament light source and the LED filament light source light.

[0147] The lamp 12 also includes a capsule 13 that at least partially encapsulates the at least one LED filament 1. The lamp 12 also includes a cap 14. Fig.12 As shown, the controller 17 is disposed within the enclosure 13. When the cap 14 is included, the controller 17 may also be disposed inside the cap 14 so that it is hidden from view. The lamp 12 also includes threads 15 for connecting to a socket and terminals 16 for connecting to a power source.

[0148] The envelope 13 of the lamp 12 may also and optionally may be provided with a coating 18 covering at least a portion of the envelope 13, such as a reflective coating.

[0149] Those skilled in the art realize that the present invention is by no means limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

[0150] Furthermore, variations to the disclosed embodiments may be understood and effected by those skilled in the art in practicing the claimed invention by studying 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 fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. A light emitting diode (LED) filament (1), the LED filament being configured to emit LED filament light (22) during operation, the LED filament comprising: An array (2) of light emitting diodes (LED), the array of light emitting diodes (LED) comprising a plurality of LEDs (20) configured to emit LED light (23) in operation, a circuit device (19) coupled to the plurality of LEDs, an elongated carrier (3), the plurality of LEDs being arranged on a first main surface (31) of the elongated carrier, an encapsulation (5), the encapsulation comprising a translucent material, the encapsulation at least partially surrounding the plurality of LEDs and the elongated carrier, and An at least partially reflective layer (4), the at least partially reflective layer: is configured to be perceived as gold by the observer, is configured to at least partially transmit and at least partially reflect the LED light, and The LEDs (20) are arranged at least on the same side of the carrier as the plurality of LEDs (20).

2. The LED filament of claim 1, wherein at least 60% of the LED light is transmitted through the at least partially reflective layer.

3. The LED filament according to any of the preceding claims, wherein the at least partially reflective layer (4) is configured to be non-conductive or electrically isolated from the circuit arrangement.

4. The LED filament according to any one of the preceding claims, wherein the LED filament (1) has an LED filament periphery, wherein at least 80% of the LED filament periphery is covered by the at least partially reflecting layer (4).

5. The LED filament according to any of the preceding claims, wherein the encapsulant (5) further comprises a luminescent material, the luminescent material being configured to at least partially convert the LED light into converted light (24), wherein the at least partially reflective layer (4) is configured to at least partially transmit and / or at least partially reflect the converted light, preferably at least 60% of the converted light is transmitted through the at least partially reflective layer.

6. An LED filament according to any one of the preceding claims 1 to 4, wherein the encapsulant (5) does not have a luminescent material, wherein the encapsulant comprises a light scattering material (26), the light scattering material being configured to at least partially scatter the LED light into scattered light (25), wherein the at least partially reflective layer (4) is configured to at least partially transmit and / or at least partially reflect the scattered light, preferably at least 60% of the scattered light is transmitted through the at least partially reflective layer.

7. The LED filament according to any one of the preceding claims, wherein the at least partially reflecting layer (4) is provided as any one or more of the following: On the package, on a surface of the elongated carrier, so as to cover at least 60% of the elongated carrier, the plurality of LEDs being arranged on the surface, on the same side of the elongated carrier as the plurality of LEDs and between the elongated carrier and the electrically insulating reflective layer so as to cover at least 60% of the elongated carrier, on the elongated carrier, around the plurality of LEDs, thereby covering at least 60% of the elongated carrier, and On or as a foil or a tube arranged around the package.

8. An LED filament according to any one of the preceding claims, wherein the elongated carrier (3) is a transparent elongated carrier, and wherein the at least partially reflecting layer (4) is arranged on a side of the elongated carrier opposite to the plurality of LEDs (20), or the at least partially reflecting layer (4) is provided on a side or surface (32) of the elongated carrier, the side or the surface extending opposite and parallel to the first main surface (31) of the elongated carrier, the plurality of LEDs being arranged on the first main surface.

9. The LED filament according to any one of the preceding claims, wherein the at least partially reflective layer (4) comprises a reflectivity of 30%-50% for light with a wavelength less than 490 nm, a reflectivity of more than 80% for light with a wavelength greater than 600 nm, and a reflectivity that gradually increases with wavelength for light with a wavelength between 490 nm and 600 nm.

10. The LED filament according to any one of the preceding claims, wherein one or more of the following applies: The surface of the LED filament (1) comprises a reflectance of less than 30%, at least 70% of said first major surface of said elongated carrier (3) is covered by said at least partially reflecting layer, The at least partially reflective layer (4) is provided with a total reflectivity in the range of 20% to 60%, The at least partially reflecting layer (4) is provided as particles or flakes in a polymer binder or a transparent polymer binder or silicone, The at least partially reflecting layer (4) is provided by using vapour deposition.

11. The LED filament according to any of the preceding claims, wherein a portion (11) of the elongated carrier (3) is not covered by the encapsulation to ensure that at least a portion of the at least partially reflecting layer is not provided with the encapsulation.

12. The LED filament according to claim 11, wherein at least 40% of the surface area of ​​the at least partially reflecting layer (4) is not provided with the encapsulant.

13. The LED filament according to any of the preceding claims, wherein the elongated carrier (3) is curved.

14. The LED filament according to any one of the preceding claims, wherein the LED filament further comprises: a further array of light emitting diodes (LEDs) (7), the further array comprising a further plurality of LEDs configured to emit further LED light in operation, and a further circuit arrangement (21) coupled to the further plurality of LEDs, the further plurality of LEDs being arranged on a second main surface (32) of the elongated carrier (3) opposite the first main surface (31), and a further at least partially reflecting layer (8), said further at least partially reflecting layer: is configured to be perceived as gold by the observer, is configured to at least partially transmit and at least partially reflect one or more of the further LED light, and Arranged at least on the same side of the elongated carrier as the further plurality of LEDs (7).

15. An LED filament lamp (12) or luminaire comprising at least one LED filament (1) according to any one of the preceding claims and a driver (17), the driver being configured to supply power to the plurality of LEDs of the LED filament via the circuit arrangement of the LED filament.

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