Spiral LED filament arrangement

Abstract

A light-emitting diode, LED, filament arrangement (1) is provided. The LED filament arrangement comprises a first LED filament (2a), a second LED filament (2b), and a third LED filament (2c). The first LED filament is configured to emit first LED filament light (3a) of a first color. The first LED filament has the shape of a spiral having a first diameter (4a). The first LED filament comprises an array of a plurality of first LEDs (10a) arranged on a first elongated carrier (7a). The second LED filament is configured to emit second LED filament light (3b) of a second color. The second filament has the shape of a spiral having a second diameter (4b). The second LED filament comprises an array of a plurality of second LEDs (10b) arranged on a second elongated carrier (7b). The third LED filament is configured to emit third LED filament light (3c) of a third color. The third LED filament has the shape of a spiral having a third diameter (4c). The third LED filament comprises an array of a plurality of third LEDs (10c) arranged on a third elongated carrier (7c). The first color, the second color, and the third color are different from each other. The second diameter is smaller than the first diameter. The third diameter is smaller than the second diameter. The first LED filament, the second LED filament, and the third LED filament are arranged concentrically around a center axis (A) of the LED filament arrangement. The first LED filament, the second LED filament, and the third LED filament are stacked in a stack in a radial direction (r) in relation to the center axis.

Description

[0001] 2024PF80090

[0002] 1

[0003] SPIRAL LED FILAMENT ARRANGEMENT

[0004] TECHNICAL FIELD

[0005] The present disclosure relates generally to the field of lighting devices. In particular, the present disclosure relates to a light emitting diode, LED, filament arrangement.

[0006] BACKGROUND

[0007] Incandescent lamps are rapidly being replaced by LED-based lighting solutions. It is nevertheless appreciated and desired by users to have retrofit lamps which have the look of an incandescent bulb.

[0008] Solid-state lighting devices may provide many advantages over their incandescent, fluorescent, and gas-discharge based counterparts. For instance, they may provide increased operational life, reduced power consumption and higher efficacy. Solidstate lighting devices, such as LEDs, are employed in a wide range of lighting applications.

[0009] Development of LED-based lighting devices is ever ongoing and may provide new solutions extending far beyond what has been possible using conventional light sources.

[0010] Document WO 2024 / 170456 discloses a LED filament arrangement comprising at least one first filament configured to emit first light having a first correlated color temperature at least one second filament configured to emit second light having a second correlated color temperature and at least one third filament configured to emit third light having a third color temperature where each of the at least one first, second and third filament comprises a carrier of elongated shape, where a plurality of light emitting diodes is arranged on the carrier and a control unit configured to control a first luminous flux of the first light, a second luminous flux of the second light and a third luminous flux of the third light according to at least one predetermined setting in order to control the total correlated color temperature of the LED filament arrangement light as a function of the at least one predetermined setting.

[0011] SUMMARY

[0012] One general aim of the present disclosure is to provide a spiral LED filament2024PF80090

[0013] 2

[0014] arrangement. Specifically, there is a desire to be able to provide a more aesthetically pleasing spiral LED filament arrangement.

[0015] This and other objects are achieved by means of a device as defined in the appended independent claim. Other embodiments are defined by the dependent claims.

[0016] According to a first aspect of the present disclosure, a light-emitting diode, LED, filament arrangement is provided. The LED filament arrangement is configured to, in operation, emit LED filament arrangement light. The LED filament arrangement comprises a first LED filament. The first LED filament is configured to emit first LED filament light of a first color. The first LED filament has the shape of a spiral having a first diameter. The first LED filament comprises an array of a plurality of first LEDs arranged on a first elongated carrier.

[0017] The LED filament arrangement comprises a second LED filament. The second LED filament is configured to emit second LED filament light of a second color. The second filament has the shape of a spiral having a second diameter. The second LED filament comprises an array of a plurality of second LEDs arranged on a second elongated carrier.

[0018] The LED filament arrangement comprises a third LED filament. The third LED filament is configured to emit third LED filament light of a third color. The third LED filament has the shape of a spiral having a third diameter. The third LED filament comprises an array of a plurality of third LEDs arranged on a third elongated carrier.

[0019] The first color is different from the second color. The first color is different from the third color. The second color is different from the third color. The second diameter is smaller than the first diameter. The third diameter is smaller than the second diameter. The first LED filament, the second LED filament, and the third LED filament are arranged concentrically around a center axis of the LED filament arrangement. The first LED filament, the second LED filament and the third LED filament are stacked (in a stack) in a radial direction in relation to the center axis.

[0020] The present disclosure relates to providing a LED filament arrangement that may provide a more aesthetically pleasing lighting device.

[0021] A LED filament is a light-emitting device that has a plurality of light emitting diodes, LEDs, arranged in a linear array. The LEDs may be arranged to emit light of different colors or spectral distributions. A LED filament has a length, a width, and an axis of elongation along the length. The length may be more than five times the width, such as more than ten times the width. A LED filament may have a first major surface and a second major surface.2024PF80090

[0022] 3

[0023] The LEDs of a LED filament are preferably arranged on an elongated carrier, such as a substrate, which may be made from a polymer, glass, quartz, metal, or sapphire. The carrier may be rigid or flexible. When the carrier has 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 transmissive for light, such as translucent, or transparent. A LED filament may be used to mimic the filament of an incandescent light bulb. A LED filament may comprise multiple sub-filaments.

[0024] LED filament light may be the combined light emitted by the LEDs of the LED filament. LED filament arrangement light may refer to the combined light emitted by the LED filaments of the LED filament arrangement.

[0025] LED filament light may be monochromatic or polychromatic, i.e., consist of more than one wavelength. As the LED filament light may be polychromatic, the LED filament light may comprise a plurality of wavelengths, or colors, however, the emitted LED filament light may be perceived as one color. For example, LED filament light may be red, blue, green, white, etc. Two colors being different means that the perceived color of the LED filaments are different from each other. For example, red and white LED filament light are different in color, even though white LED filament light may include wavelengths in the red spectrum.

[0026] The color of a LED filament may be described as a color point, defined by a first coordinate, x, and a second coordinate, y, in a color space, such as the CIE 1931 color space. The first color may be described by a first color point, defined by the first coordinate xi and a second coordinate yi. The second color may be described by a second color point, with a first coordinate X2 and a second coordinate yi. The third color may be described by a third color point, with a first coordinate X3 and a second coordinate ys. The ratio between the first coordinate of the first color point and the second color point, i.e., X1 / X2, may be smaller than or equal to 0.9 or larger than or equal to 1.1. The ratio between the second coordinate of the first color point and the second color point, i.e., yi / y2, may be smaller than or equal to 0.9 or larger than or equal to 1.1. The ratio between the first coordinate of the first color point and the third color point, i.e., X1 / X3, may be smaller than or equal to 0.9 or larger than or equal to 1.1. The ratio between the second coordinate of the first color point and the third color point, i.e., yi / y3, may be smaller than or equal to 0.9 or larger than or equal to 1.1. The ratio between the first coordinate of the second color point and the third color point, i.e., X2 / X3, may be smaller than or equal to 0.9 or larger than or equal to 1.1. The ratio between the2024PF80090

[0027] second coordinate of the second color point and the third color point, i.e., y2 / ys, may be smaller than or equal to 0.9 or larger than or equal to 1.1.

[0028] Expressed differently:

[0029] — < 0.9 or — > 1.1 and / or — < 0.9 or — > 1.1 may be fulfilled,x2x2 V2 V2

[0030]

[0031] < > < > 1.1 may be fulfilled,x3xs y3y3

[0032] — < 0.9 or — > 1.1 and / or — < 0.9 or — > 1.1 may be fulfilled.

[0033] x3x3y3y3

[0034] A spiral may be a three-dimensional curve that spirals around a center axis while continuously moving along the center axis. A spiral may have the shape of a helix and / or have a coiled shape. A diameter of a spiral may be the distance between two outermost points of the spiral, measured along a path passing through the center axis, projected on an axis perpendicular to the center axis. An axis perpendicular to the center axis, which intersects the center axis, may be defined as a radial axis. The radius of a spiral may be seen as the distance, along a radial axis, from a point on the spiral to a center axis. The radius of a spiral may vary along the length of the spiral. The radius of a spiral may be constant along the length of the spiral. The diameter of the spiral may, in some examples, be seen as double the radius of the spiral. The diameter may be an average(d) diameter.

[0035] A LED filament having the shape of a spiral may mean that the length of the LED filament extends so as to form a spiral shape around a center axis. The LED filament may be arranged so that the same surface, e.g., a first major surface, is facing towards the center axis, for example, along the whole extension of the LED filament. A LED filament may be positioned concentrically around a center axis about which it spirals. Multiple LED filaments may be positioned concentrically around the same center axis.

[0036] The first LED filament, the second LED filament and the third LED filament are stacked (in a stack) in a radial direction in relation to a center axis. LED filament being stacked in a radial direction in relation to a center axis may mean that the LED filaments are positioned at least partially overlapping, as seen radially outwards from a center axis.

[0037] Preferably, the first LED filament, the second LED filament, and the third LED filament significantly overlap, such as fully overlap. By stacking the LED filaments in a radial direction in relation to the center axis, the LED filament arrangement may provide the appearance, from certain angles, of comprising a single spiral shaped LED filament.

[0038] A first major surface of a LED filament may be closer to the center axis as compared to the second major surface of the same LED filament. Since the LED filament is curving, the inner surface of the LED filament may be shorter than an outer surface of the2024PF80090

[0039] 5

[0040] LED filament. The first major surface of a LED filament may therefore be shorter than the second major surface of the same LED filament. A length of a spiral shaped LED filament depends on the extension along a center axis of said LED filament, the number of turns or revolutions around the center axis, and the diameter of the spiral shape of said LED filament. A LED filament that is arranged radially further away from a center axis, i.e., arranged in a spiral having a larger diameter, may be longer than a LED filament arranged closer to the center axis. More specifically, the first major surface of a LED filament may be the same length or longer than the second major surface of a LED filament that is arranged closer to the center axis. For example, as the first diameter is larger than the second diameter, the first LED filament may be longer than the second LED filament.

[0041] LED filaments of different lengths may allow for an alignment of two or more LED filaments, at one or two ends, along a first line extending radially from the center axis. This may allow for a more aesthetically pleasing lighting device, at least since it may give the appearance of a single LED filament.

[0042] The arrangement of the first LED filament, the second LED filament, and the third LED filament may provide the appearance of a single LED filament arrangement from certain angles. The LED filament arrangement may be seen as having a (single) spiral shape arranged concentrically around a center axis. Stacking LED filaments in a radial direction, rather than in a direction parallel with the center axis, may provide the appearance of a slimmer LED filament or spiral shape. For the same extension along the center axis, the present LED filament arrangement may form a spiral shape including a larger number of revolutions in relation to a LED filament arrangement in which LED filaments are stacked (in a stack) in parallel with the center axis. Moreover, the present LED filament arrangement may allow for an increased distance between LED filaments of different revolutions, as compared with a LED filament arrangement in which LED filaments are stacked (in a stack) in parallel with the center axis.

[0043] Further, the present LED filament arrangement may provide an appearance that more closely resembles traditional light-emitting filaments, such as the filament of an incandescent light bulb. A closer resemblance to traditional light emitting filaments may allow for a more aesthetically pleasing lighting device.

[0044] Stacking a first LED filament, a second LED filament, and a third LED filament with different colors may provide a LED filament arrangement light with a wide color range and increased brightness. A light emission of each LED filament in the arrangement may be independently or jointly controllable. A hue of the LED filament2024PF80090

[0045] 6

[0046] arrangement light may be tuned by, independently or jointly, controlling the intensity or the wavelength of one or more of the LED filament lights emitted by the respective LED filaments.

[0047] Furthermore, stacking LED filaments in a radial direction relative to the center axis may allow for a more uniform mixing of light, more specifically, a more uniform mixing of the first color, the second color, and the third color. This may allow for a more uniform illumination pattern. Stacking a first LED filament, a second LED filament, and a third LED filament in a radial direction may allow for a more aesthetically pleasing lighting device.

[0048] According to some embodiments, the LED filament arrangement may further comprise a fourth LED filament. The fourth LED filament may be configured to emit fourth LED filament light of a fourth color. The fourth LED filament may have the shape of a spiral having a fourth diameter. The fourth LED filament may comprise an array of a plurality of fourth LEDs arranged on a fourth elongated carrier. The fourth color may be different from the first color, the second color, and the third color. The fourth diameter may be smaller than the third diameter. The first LED filament, second LED filament, the third LED filament, and the fourth LED filament may be arranged concentrically around the center axis of the LED filament arrangement. The first LED filament, the second LED filament, the third LED filament, and the fourth LED filament may be stacked in the radial direction in relation to the center axis.

[0049] A larger number of LED filaments may allow for a larger number of colors, which may allow for an LED filament arrangement light with a wider color range, increased brightness, and / or improved color mixing.

[0050] The fourth color may be described as a fourth color point, defined by a first coordinate X4 and a second coordinate y4 in the color space. The ratio between the first coordinate of the first color point and the fourth color point, i.e., X1 / X4, may be smaller than or equal to 0.9 or larger than or equal to 1.1. The ratio between the second coordinate of the first color point and the fourth color point, i.e., yi / y4, may be smaller than or equal to 0.9 or larger than or equal to 1.1. The ratio between the first coordinate of the second color point and the fourth color point, i.e., X2 / X4, may be smaller than or equal to 0.9 or larger than or equal to 1.1. The ratio between the second coordinate of the second color point and the fourth color point, i.e., y? / y4, may be smaller than or equal to 0.9 or larger than or equal to 1.1. The ratio between the first coordinate of the third color point and the fourth color point, i.e., X3 / X4, may be smaller than or equal to 0.9 or larger than or equal to 1.1. The ratio between the second2024PF80090

[0051] coordinate of the third color point and the fourth color point, i.e., ys / y-r may be smaller than or equal to 0.9 or larger than or equal to 1.1.

[0052] Expressed differently:

[0053] < > < > 1.1 may be fulfilled,

[0054]

[0055]

[0056]

[0057]

[0058] < 0.9 or

[0059]

[0060] > 1.1 and / or — < 0.9 or — > 1.1 may be fulfilled,

[0061]

[0062]

[0063] < 0.9 or

[0064]

[0065] > 1.1 and / or — < 0.9 or — > 1.1 may be fulfilled.

[0066]

[0067] The first LED filament, the second LED filament, the third LED filament, and the fourth LED filament may be stacked in a radial direction in relation to the center axis. Preferably, the first LED filament, the second LED filament, the third LED filament, and the fourth LED filament significantly overlap, such as fully overlap, in the radial direction.

[0068] Stacking a first LED filament, a second LED filament, a third LED filament, and a fourth LED filament may allow for further improved aesthetical and functional properties.

[0069] Preferably at least 90% or at least 95% of the first LED filament, the second LED filament, and the third LED filament (and optionally the fourth LED filament) may be (continuously) connected to neighboring, i.e., adjacent, LED filament(s). Preferably the first, second and third LED filament (and optionally the fourth LED filament) may have the same pitch with (substantially) zero phase shift. The spiral shape of the first, second and third LED filament (and optionally the fourth LED filament) may be a 3D spiral or a helix. The length of the first, second and third LED filament (and optionally the fourth LED filament) may be different. The length of the first LED filament may be longer than the length of the second LED filament, and the length of the second LED filament may be longer than the length of the third LED filament (and optionally the length of the third LED filament may be longer than the length of the optional fourth LED filament). The differences in length of neighboring LED filaments may be at least 2% or at least 5%.

[0070] According to some embodiments, one of the LED filaments may be configured to emit white light having a correlated color temperature in a range from 1700K to 6500K, and optionally a color rendering index of at least 80.

[0071] Corrected color temperature (CCT) is a measure of the color appearance of light, indicating how warm or cool the light appears. One of the LED filaments may be configured to emit white light having a correlated color temperature in a range from 1700K to 2500K. A CCT range of light, such as light in a range from 1700K to 6500K or more2024PF80090

[0072] 8

[0073] specifically in a range from 1700K to 2500K, may provide further aesthetic and functional properties based on the warmness or coolness of the light.

[0074] White light includes a broad spectrum of wavelengths, as compared to monochromatic light, such as red, green, or blue. A broad wavelength spectrum may allow for a more even illumination. White light may have a higher luminous flux, e.g., a higher total amount of visible light emitted by a light source, as compared to monochromatic light sources with the same energy output.

[0075] According to some embodiments, one of the LED filaments may be configured to emit red light. Another one of the LED filaments may be configured to emit green light. Still another one of the LED filaments may be configured to emit blue light.

[0076] Red, green, and blue are primary colors in the additive color model and may therefore allow for color mixing that produces a wide range of colors, including, but not limited to, white light. Using a red, green, and blue light source may allow for a more efficient and more dynamic color mixing where a wider range of colors can be created.

[0077] For example, the first LED filament may be configured to emit red light, the second LED filament may be configured to emit green light and the third LED filament may be configured to emit blue light. Alternatively, and as another example, the second LED filament may be configured to emit red light, the third LED filament may be configured to emit green light and the fourth LED filament, if provided, may be configured to emit blue light. Thus, the wavelength of the emitted light, more specifically the wavelength of emitted red, green, and blue light, may be ordered so as to increase with a further distance from the center axis.

[0078] Including a LED filament emitting red light, a LED filament emitting green light and a LED filament emitting blue light may provide further improved aesthetic and functional properties.

[0079] According to some embodiments, one of the LED filaments may be configured to emit white light having a correlated color temperature in a range from 1700K to 6500K and a color rendering index of at least 80. Another one of the LED filaments may be configured to emit red light. Yet another one of the LED filaments may be configured to emit green light. Still another one of the LED filaments may be configured to emit blue light.

[0080] According to some embodiments, the stack of the first LED filament, the second LED filament, the third LED filament and, when provided, the fourth LED filament may have a stack thickness, ST, and a stack width, SW, wherein ST / SW>2.2024PF80090

[0081] 9

[0082] The stack thickness, ST, may be measured along the radial direction and / or defined perpendicular to a major surface of the first, second and / or third elongated carrier. The stack width, SW, may be measured perpendicular to the stack thickness. Preferably, ST / SW>2, more preferably ST / SW>2.5, most preferably ST / SW>3. ST / SW may be referred to as the thickness to width ratio.

[0083] While LED filaments on the market have a thickness to width ratio of 1 or less, typically around 0.5, the LED filament according to the invention may have a thickness to width ratio of at least 2. A higher thickness to width ratio may provide further improved aesthetic and functional properties.

[0084] According to some embodiments, the first LED filament may be configured to emit white light having a correlated color temperature in a range from 1700K to 6500K. The first LED filament may optionally have a color rendering index of at least 80 or at least 90.

[0085] The first LED filament has a spiral shape having a first diameter, larger than the second diameter, the third diameter, and, when provided, the fourth diameter. Thus, the first LED filament is stacked at a higher radial distance from the center axis as compared to the other LED filaments. In other words, the first LED filament may be arranged furthest from the center axis. Having a white LED filament stacked furthest out from the center axis may improve the luminous flux of the LED filament arrangement.

[0086] By configuring the outer LED filament of the stack to emit white light, the LED filament arrangement may provide the appearance of a single white LED filament.

[0087] According to some embodiments, a LED filament that is arranged the closest to the center axis may be configured to emit blue light.

[0088] The third LED filament, arranged at a third diameter smaller than the first diameter and the second diameter, is arranged closest to the center axis when the fourth LED filament is not provided. When the fourth LED filament is provided, the fourth LED filament is arranged closest to the center axis.

[0089] Arranging a LED filament configured to emit blue light closest to the center axis may be especially suitable for embodiments wherein, for example, one or more of the other LED filaments may be phosphor-converting LED filament. Further advantages may be provided by separating a LED filament configured to emit white light and a LED filament configured to emit blue light, for example by another LED filament. Specifically, cross-talk between the blue-emitting LED filament and a phosphor-converting LED filament, e.g., a white-emitting LED filament, may be reduced by providing a separation between the blue-2024PF80090

[0090] 10

[0091] emitting and the phosphor-converting LED filament. A LED filament configured to emit white light may comprise a LED configured to emit blue light together with at least one luminescent material, such as a phosphor, configured to convert at least some of the blue light to lights of other wavelengths and colors. The combination of the blue light and the converted light may appear as white light. Therefore, a LED filament configured to emit blue light might interfere with a luminescent material of an adjacent LED filament configured to emit white light. Specifically, some of the blue light emitted by the blue-emitting LED filament may be converted to light of other wavelengths and colors, which may result in a combined light comprising less blue light than intended. A LED filament comprising an LED and a phosphor configured to convert at least some of the light from the LED to converted light may be referred to as a phosphor-converting LED filament.

[0092] According to some embodiments, a LED filament that is arranged between the first LED filament and a LED filament that is arranged the closest to the center axis may be configured to emit red light.

[0093] If the fourth LED filament is provided, it is arranged closest to the center axis. In embodiments not including a fourth LED filament, the third LED filament is arranged closest to the center axis. A filament that is arranged between the first LED filament and the LED filament that is arranged the closest to the center axis may therefore be the second LED filament or the third LED filament, if the fourth LED is provided. In embodiments not including a fourth LED filament, a filament that is arranged between the first LED filament and the LED filament that is arranged the closest to the center axis may be the second LED filament.

[0094] Arranging a LED filament configured to emit red light between the first LED filament and a LED filament that is arranged the closest to the center axis may be especially suitable in embodiments in which, for example, one or more of the other LED filaments may be a phosphor-converting LED filament. Further advantages may be provided by arranging a LED filament configured to emit red light between a phosphor-converting LED filament, e.g., a LED filament configured to emit white light, and a LED filament configured to emit blue light. Specifically, cross-talk between the blue-emitting LED filament and the whiteemitting LED filament may be further reduced by arranging a red-emitting LED filament between the blue- and white-emitting LED filaments. Some red luminescent materials, such as KSiF, may only be excited by blue light. Thus, if a red-emitting LED filament is arranged between the blue-emitting and the white-emitting LED filaments, stray light from the blueemitting LED filament may be converted to red light by luminescent material of the red-2024PF80090

[0095] 11

[0096] emitting LED filament, before reaching the white-emitting LED filament. Thus, interference by the blue light of the white light may be reduced.

[0097] According to some embodiments, the first LED filament may be configured to emit more than 50% of the first LED filament light away from the center axis.

[0098] More specifically, the first LED filament may be configured to emit more than 50%, more than 60%, or more than 70%, of the first LED filament light away from the center axis. A LED filament configured to emit more than 50% or more than 60%, such as at least 70%, of the respective LED filament light away from the center axis may mean that a majority of the light emitted by the LED filament is emitted at an angle deviating less than 90 degrees from a radial axis.

[0099] Emitting a majority of the light emitted by the first LED filament away from the center axis may reduce the amount of light that is reflected and / or scattered by components positioned at a smaller radial distance from the center axis as compared to the first LED filament. Emitting a majority of the light emitted by the first LED filament away from the center axis may cause first LED filament light to be emitted in a direction towards an area or an object that is to be illuminated, causing the area or the object to be under direct lighting. Emitting a majority of the light emitted by the first LED filament away from the center axis may provide an increased brightness.

[0100] Emitting a majority of the first LED filament light away from the center axis may also allow for a more efficient LED filament arrangement, as it may decrease the amount of first LED filament light that is blocked by other LED filaments.

[0101] Emitting more than 50%, or more than 60%, such as at least 70%, of the first LED filament light away from the central axis may provide further improved aesthetic and functional properties.

[0102] According to some embodiments, the LED filament that is arranged the closest to the center axis may be configured to emit more than 50% of its emitted light in directions towards the center axis.

[0103] The LED filament that is arranged the closest to the center axis may be configured to emit more than 50%, more than 60%, or more than 70%, of its emitted light in directions towards the center axis. A LED filament configured to emit more than 50% or more than 60%, such as at least 70%, of the respective LED filament light towards the center axis may mean that a majority of the light emitted by the LED filament is emitted at an angle deviating more than 90 degrees from a radial axis.2024PF80090

[0104] 12

[0105] The LED filament closest to the center axis emitting light in a direction towards the center axis may decrease the amount of light that is reflected and / or scattered by the other LED filaments. This may allow for an increased brightness and improved aesthetic and functional properties. The LED filament arranged the closest to the center axis emitting a majority of light towards the center axis may allow for a more efficient LED filament arrangement as it may decrease the amount of LED filament light that is blocked by other LED filaments.

[0106] Emitting more than 50%, or more than 60%, such as at least 70%, of light emitted by the LED filament arranged closest to the center axis towards the center axis may provide further improved aesthetic and functional properties.

[0107] According to some embodiments, a LED filament that is arranged between the first LED filament and the LED filament that is arranged the closest to the center axis may be configured to emit more than 50% of its emitted light in a direction along the center axis. A LED filament that is arranged between the first LED filament and the LED filament that is arranged the closest to the center axis may be configured to emit more than 50%, more than 60%, or more than 70%, of its emitted light in a direction along the center axis.

[0108] Emitting light along a center axis may include emitting light in a direction that does not deviate more than 15 degrees from the direction of the center axis. In embodiments including a fourth LED filament, at least one of the second LED filament and the third LED filament may be configured to emit more than 50%, or more than 60%, such as at least 70%, of their emitted light in a direction along the center axis.

[0109] A LED filament that is arranged between the first LED filament and the LED filament that is arranged the closest to the center axis may be radially overlapping with other LED filaments, positioned at a larger or a smaller radial distance from the center axis.

[0110] Emitting light in a direction along the center axis may decrease the amount of light that is reflected and / or scattered by other LED filaments, which may increase the brightness and / or increase the efficiency of the LED filament arrangement.

[0111] Having a LED filament that is arranged between the first LED filament and the LED filament that is arranged the closest to the center axis emitting more than 50%, or more than 60%, such as at least 70%, of its light along the center axis may provide further improved aesthetic and functional properties.

[0112] According to some embodiments, the elongated carriers of at least one or at least two of the LED filaments may have a reflectivity of at least 70% for visible light.2024PF80090

[0113] 13

[0114] For example, the elongated carriers of at least one or at least two of the LED filaments may have a reflectivity of at least 80%, such as 85%, for visible light.

[0115] Reflectivity refers to the ability of a surface to reflect light. A higher reflectivity means that more light is reflected. A higher reflectivity may improve efficiency of a system, for example, by directing light, instead of absorbing or transmitting it. Decreasing the amount of light that is transmitted may be advantageous as it may prevent or limit undesired inference between the different LED filament lights which have different colors.

[0116] The elongated carriers of at least one or at least two of the LED filaments having a reflectivity of at least 70%, at least 80%, or at least 85% for visible light may provide further improved aesthetic and functional properties.

[0117] According to some embodiments, the LED filaments may be affixed one to each other by an adhesive material or by one or more holders.

[0118] Affixing the LED filaments one to each other may include affixing the first LED filament to the second LED filament, affixing the second LED filament to the third LED filament, and, when provided, affixing the third LED filament to the fourth LED filament. Affixing the LED filaments to each other may include affixing two or more LED filaments to each other.

[0119] The adhesive material may be an additional glue layer and / or may form part of an encapsulant. The one or more (e.g. at least three or at least five) holders may be (metal or plastic) clamps or rings.

[0120] Adhesive materials may, for example, include glue, epoxy, hot-melt, and / or tapes. A holder may hold two or more LED filaments in substantially stationary position in relation to each other.

[0121] Affixing LED filaments to each other may improve the durability and / or robustness of the LED filament arrangement. Improving durability and / or robustness may improve aesthetics of the LED filament arrangement, in particular over time as it may prevent or reduce the effects of possible deteriorations of the LED filament arrangement.

[0122] Affixing LED filaments one to each other may provide further improved aesthetic and functional properties.

[0123] According to some embodiments, the LED filament arrangement may further comprise a common elongated carrier, wherein the common elongated carrier may comprise the first and the second elongated carriers.2024PF80090

[0124] 14

[0125] According to some embodiments, the LED filament arrangement may further comprise a common elongated carrier, wherein the common elongated carrier may comprise the second and the third elongated carriers.

[0126] According to some embodiments, the LED filament arrangement may further comprise a common elongated carrier, wherein the common elongated carrier may comprise the third and the fourth elongated carriers.

[0127] A common elongated carrier may comprise two elongated carriers. For example, the two elongated carriers may form a single unit. Alternatively, the two elongated carriers may be positioned adjacently and / or abutting. For example, in a single common elongated carrier, one elongated surface may be referred to as one carrier and another opposite elongated surface may be referred to as another carrier. Two elongated carriers positioned adjacently and / or abutting, thereby forming a common elongated carrier, may have LEDs on opposite sides. In the common carrier, one set or array of LEDs may be arranged on one elongated surface, forming one elongated carrier, arranged facing away from the center axis. Another set or array of LEDs may be arranged on another, opposite elongated surface, forming another elongated carrier, arranged facing towards the center axis.

[0128] Using a common elongated carrier may reduce the radial extent, or a thickness, of the stack of LED filaments, which may provide aesthetic and functional properties.

[0129] The LED filament arrangement may comprise a first common elongated carrier and a second common elongated carrier. For example, in embodiments including the fourth LED filament, the first common elongated carrier may comprise the first and the second elongated carriers, and the second common elongated carrier may comprise the third and the fourth elongated carriers.

[0130] According to some embodiments, at least one or two of the following may apply: the first LED filament comprises a first elongated encapsulant, the second LED filament comprises a second elongated encapsulant, the third LED filament comprises a third elongated encapsulant, and / or, when provided, a fourth LED filament comprises a fourth elongated encapsulant.

[0131] The first LED filament may comprise a first elongated encapsulant at least partly covering the first elongated carrier and at least partly enclosing the plurality of first LEDs. The first elongated encapsulant may comprise a first luminescent material configured to at least partly convert a first LED light emitted by the plurality of first LEDs into a first converted light;2024PF80090

[0132] 15

[0133] The second LED filament may comprise a second elongated encapsulant at least partly covering the second elongated carrier and at least partly enclosing the plurality of second LEDs. The second elongated encapsulant may comprise a second luminescent material configured to at least partly convert a second LED light emitted by the plurality of second LEDs into a second converted light;

[0134] The third LED filament may comprise a third elongated encapsulant at least partly covering the third elongated carrier and at least partly enclosing the plurality of third LEDs. The third elongated encapsulant may comprise a third luminescent material configured to at least partly convert a third LED light emitted by the plurality of third LEDs into a third converted light; and

[0135] The fourth LED filament, when provided, may comprise a fourth elongated encapsulant at least partly covering the fourth elongated carrier and at least partly enclosing the plurality of fourth LEDs. The fourth elongated encapsulant may comprise a fourth luminescent material configured to at least partly convert the fourth LED light emitted by the plurality of fourth LEDs into a fourth converted light.

[0136] An elongated encapsulant at least partly covering an elongated carrier may cover a portion of, or the whole, elongated carrier, such that one or more or the LEDs of said elongated carrier are at least partially covered by an encapsulant. An elongated encapsulant at least partly enclosing the plurality of LEDs of a LED filament may house or encapsulate two or more of the LEDs of said LED. An elongated encapsulant may protect components from, for example, environmental factors such as moisture or dust.

[0137] A LED filament may comprise an encapsulant that at least partly covers one or more of the LEDs of the LED filament. The encapsulant may at least partly cover one or more of the first major surface and second major surface of the elongated carrier. The encapsulant may scatter light emitted by one or more LEDs. For example, the encapsulant may comprise a scattering agent. The encapsulant may comprise a polymer, which may be flexible, such as a silicone. The encapsulant may be transparent. The encapsulant may comprise a luminescent material, such as a phosphor, for converting at least some of the light emitted by the LEDs to light of a different wavelength. The LED filament light may comprise LED light and / or converted light. For example, first LED filament light may comprise light from one or more first LEDs and / or first converted light, i.e., light originating from one or more first LEDs that has been converted to light of a different wavelength.2024PF80090

[0138] 16

[0139] Using an elongated encapsulant, such as a first elongated encapsulant, a second elongated encapsulant, a third elongated encapsulant and / or a fourth elongated encapsulant, may provide further improved aesthetic and functional properties.

[0140] In an alternative embodiment, instead of using a first luminescent material, a second luminescent material, a third luminescent material (and / or a fourth luminescent material), a first light-scattering material, a second light-scattering material, a third lightscattering material (and / or a fourth light-scattering material) may be used. The first lightscattering material may be configured to at least partly scatter a first LED light emitted by the plurality of first LEDs into a first scattered light, the second light-scattering material may be configured to at least partly scatter a second LED light emitted by the plurality of second LEDs into a second scattered light, the third light-scattering material may be configured to at least partly scatter a third LED light emitted by the plurality of third LEDs into a third scattered light (and / or the fourth light-scattering material may be configured to at least partly scatter a fourth LED light emitted by the plurality of fourth LEDs into a fourth scattered light). Using a light-scattering material may provide further improved aesthetic and functional properties.

[0141] According to a second aspect of the present disclosure, a lamp or a luminaire is provided. The lamp or the luminaire comprises an LED filament arrangement, in accordance with the first aspect of the present disclosure, and optionally a casing that is at least partially transmissive to LED filament arrangement light.

[0142] The casing may, e.g., be an envelope. A lamp or luminaire comprising a LED filament arrangement and casing may provide further improved aesthetic and functional properties.

[0143] Further objectives of, features of, and advantages with the present invention will become apparent when studying the following detailed disclosure, the drawings, and the appended claims. Those skilled in the art realize that different features of the present invention, even if recited in different claims, can be combined in embodiments other than those described in the following.

[0144] BRIEF DESCRIPTION OF DRAWINGS

[0145] Exemplifying embodiments will now be described in more detail, with reference to the following appended drawings:

[0146] Figs, la and lb are schematic illustrations of a LED filament arrangement, in accordance with some embodiments;2024PF80090

[0147] 17

[0148] Figs. 2a and 2b are schematic illustrations of parts of a LED filament, in accordance with some embodiments;

[0149] Fig. 2c is a schematic illustration of a cross-section of a LED filament arrangement, in accordance with some embodiments;

[0150] Figs. 3a and 3b are schematic illustrations of LED filaments, in accordance with some embodiments;

[0151] Fig. 4 is a schematic illustration of a LED filament arrangement, in accordance with some embodiments;

[0152] Fig. 5 is a schematic illustration of a LED filament arrangement, in accordance with some embodiments;

[0153] Figs. 6a and 6b are schematic illustrations of cross-sections of a LED filament arrangement, in accordance with some embodiments;

[0154] Fig. 7 is a schematic illustration of a lamp or luminaire, in accordance with some embodiments.

[0155] As illustrated in the figures, the sizes of the elements and regions may be exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of the embodiments. Like reference numerals refer to like elements throughout.

[0156] DETAILED DESCRIPTION

[0157] Exemplifying embodiments will now be described more fully hereinafter with reference to the accompanying drawings in which currently preferred embodiments are shown. The 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.

[0158] With reference to Figures la and lb, a light emitting diode, LED, filament arrangement 1, in accordance with some embodiments, will be described. Figure la illustrates a LED filament arrangement 1 in a perspective view, while Figure lb illustrates the LED filament arrangement 1 in a top-down view.

[0159] The LED filament arrangement 1 comprises a first LED filament 2a, a second LED filament 2b, a third LED filament 2c, and a fourth LED filament 2d. It will be appreciated that the fourth LED filament 2d is optional. In other words, a LED filament arrangement 1 in accordance with the present disclosure may comprise a first LED filament2024PF80090

[0160] 18

[0161] 2a, a second LED filament 2b and a third LED filament 2c, without comprising a fourth LED filament 2d.

[0162] In the following, the first LED filament 2a, the second LED filament 2b, the third LED filament 2c, and the fourth LED filament 2d, may collectively be referred to as the LED filaments 2a, 2b, 2c, 2d, or the LED filaments 2a-2d. The same applies, mutatis mutandis, to other features indicated by a number followed by a letter.

[0163] The LED filament arrangement 1 is configured to emit LED filament arrangement light 3. Each of the LED filaments 2a-2d comprise a plurality of LEDs arranged on an elongated carrier. The internal structure of the LED filaments 2a-2d will be described in more detail below with reference to Figures 2a and 2b.

[0164] The first LED filament 2a, the second LED filament 2b, the third LED filament 2c, and the (optional) fourth LED filament 2d are respectively configured to emit first LED filament light, second LED filament light, third LED filament light, and fourth LED filament light. The LED filament arrangement light 3 may be a combination of the first LED filament light, the second LED filament light, the third LED filament light, and the fourth LED filament light.

[0165] The first LED filament 2a, the second LED filament 2b, the third LED filament 2c, and the fourth LED filament 2d may be configured to emit light of colors which are different from each other. More specifically, a first color of the first LED filament light, a second color of the second LED filament light, a third color of the third LED filament light, and a fourth color of the fourth LED filament light may all be different from each other.

[0166] The first LED filament 2a, the second LED filament 2b, the third LED filament 2c, and the fourth LED filament 2d each, respectively, have a shape of a spiral arranged concentrically around a center axis A.

[0167] Specifically, as is illustrated in Figure lb, first LED filament 2a forms a spiral shape having a constant first inner radius 4a, i.e. the distance between the center axis A and a point on the first, radially innermost, surface of the LED filament 2a is constant, regardless of which radial axis r, perpendicular to the center axis A and intersecting the center axis A, it is measured along. The first LED filament 2a further has a constant first outer radius 23a, i.e., the distance between the center axis A and a point on the second, radially outermost, surface of the LED filament 2a is constant regardless of which radial axis r, perpendicular to the center axis A, it is measured along.

[0168] Similarly, the second LED filament 2b is illustrated as having a constant second inner radius 4b and a constant second outer radius 23b. The third LED filament 2c is2024PF80090

[0169] 19

[0170] illustrated as having a constant third inner radius 4c and a constant third outer radius 23c. The fourth LED filament 2d is illustrated as having a constant fourth inner radius 4d and a constant fourth outer radius 23d. The first inner radius 4a is smaller than the first outer radius 23a. The second inner radius 4b is smaller than the second outer radius 23b. The third inner radius 4c is smaller than the third outer radius 23c. The fourth inner radius 4d is smaller than the fourth outer radius 23d. The difference between the inner radius 4a, 4b, 4c, 4d and the respective outer radius 23a, 23b, 23c, 23d, that belongs to the same LED filament 2a, 2b, 2c, 2d, is constant. In other words, the thickness of each of the LED filaments 2a, 2b, 2c, 2d is constant in Figure lb.

[0171] However, in other embodiments, at least one of the LED filaments 2a, 2b, 2c, 2d may have an inner radius 4a, 4b, 4c, 4d and / or outer radius 23a, 23b, 23c, 23d that is not constant, for example if the respective LED filament 2a, 2b, 2c, 2d is twisted, has an thickness that varies, or has if the spiral shape of the respective LED filament 2a, 2b, 2c, 2d is not circular, as seen from a top-down view.

[0172] The spiral shape of each of the LED filaments 2a-2d has the same pitch p. I.e., for each of the LED filaments 2a-2d, the distance p between subsequent loops of the spiral shape is the same. In the illustrated embodiment, the pitch p is constant along a length of the spiral. However, in some embodiments, the pitch may vary along a length of the LED filaments 2a-2d.

[0173] The first LED filament 2a, the second LED filament 2b, the third LED filament 2c, and the fourth LED filament 2d are stacked (in a stack) in a radial direction r in respect to the center axis A. That is, the LED filaments 2a-2d are arranged such that a line r which extends radially from the center axis A and passes through the innermost LED filament 2d also passes through the other LED filaments 2a-2c. The LED filaments 2a-2d may have a similar, or equal, thickness, such that any radial line r extending perpendicularly from the center axis A which passes through one of the LED filaments 2a-2d, also passes through all the LED filaments 2a-2d.

[0174] The fourth LED filament 2d is arranged closest to the center axis A. The third LED filament 2c is arranged closer to the center axis A than the second LED filament 2b and the first LED filament 2a. The second LED filament 2b is arranged closer to the center axis than the first LED filament 2a. The first LED filament 2a is arranged the furthest from the center axis A. In other words, the second outer radius 23b is smaller than or equal to the first inner radius 4a. The third outer radius 23c is smaller than or equal to the second inner radius 4b. The fourth outer radius 23d is smaller than the third inner radius 4c.2024PF80090

[0175] 20

[0176] In Figure lb, the difference between the first inner radius 4a and the second outer radius 23b is constant. The difference between the second inner radius 4b and the third outer radius 23c is constant. The difference between the third inner radius 4c and the fourth outer radius 23d is constant. In other words, the spacings between the LED filaments 2a, 2b, 2c, 2d are constant.

[0177] By stacking the LED filaments 2a, 2b, 2c, 2d in a radial direction in relation to the center axis A, the LED filament arrangement 1 may provide the appearance, from at least some angles, of comprising a single spiral shaped LED filament that is concentrically arranged around the center axis A.

[0178] The LED filament arrangement 1 has a first endpoint 11 and a second endpoint 12, defining the start and the end of the spiral shaped LED filament arrangement 1. The first LED filament 2a, the second LED filament 2b, the third LED filament 2c, and the fourth LED filament 2d each, respectively, have one end at the first endpoint 11 and one end at the second endpoint 12.

[0179] The LED filament arrangement 1 comprises a support structure 17 supporting the LED filaments 2a-2d. The support structure 17 comprises a stem 18, holders 20, and supporting elements 25. The stem 18 extends parallel to the center axis A. The LED filament arrangement 1 is arranged such that it spirals around the stem 18. Ten holders 20 are extending from the stem 18. The holders 20 may, alternatively, be attached to the stem in another configuration, e.g., the number of holders 20 and their positions may be different. There may be zero, one, two or more holders 20. Note that only one holder 20 is numbered in Figure 1. The holders 20 are spaced apart from each other along the length of the stem 18. The holders 20 are arranged on opposite sides of the stem 18 in an alternating manner. The holders 20 extend orthogonally to the longitudinal direction of the central axis A. It is to be understood that the holders 20, or more specifically the parts of the holders 20 that are closest to the stem 18, may extend from the stem 18 any direction that forms a non-zero angle with the stem 18.

[0180] The support structure 17, or, more specifically, the holders 20, are configured to support and / or hold the LED filaments 2a-2d, which may improve the robustness of the LED filament arrangement 1. In particular, the holders 20 may assist in preserving the relative arrangement of the LED filaments 2a, 2b, 2c, 2d in relation to each other and / or in relation to the stem 18. Each holder 20 holds a portion of the LED filament arrangement 1. Each holder 20 comprises an opening 21. Note that only one opening 21 is numbered in Figure 1. The LED filament arrangement 1 is arranged to extend through the openings 21.2024PF80090

[0181] 21

[0182] The support structure 17 has supporting elements 25 connected to the first endpoint 11 and the second endpoint 12. The supporting elements 25 may support the LED filaments 2a, 2b, 2c, 2c.

[0183] With reference to Figures 2a and 2b, the LED filaments will be further described. Figure 2a illustrates a top-down view, and Figure 2b illustrates a side view, of a section of a LED filament 2a, 2b, 2c, 2d. It is to be understood that, while only one LED filament 2a-2d is illustrated, the features and functions described may apply to all LED filaments 2a-2d. It is also to be understood that the LED filaments 2a-2d may be different from each other.

[0184] In the Figures, the section of the LED filament 2a-2d is illustrated as straight, although it may, when mounted in an LED filament arrangement, such as a LED filament arrangement 1 of Figure la, be arranged to form at least a portion of a spiral shape.

[0185] The LED filament 2a, 2b, 2c, 2d comprises an elongated carrier 7a, 7b, 7c, 7d, with a first major surface 8a, 8b, 8c, 8d and a second major surface 9a, 9b, 9c, 9d. The elongated carrier 7a-7d may be referred to as a carrier 7a-7d. The first surface 8a-8d of the carrier 7a-7d is opposite to the second surface 9a-9d.

[0186] The LED filament 2a, 2b, 2c, 2d comprises a plurality of LEDs 10a, 10b, 10c, lOd arranged in linear array on the first major surface 8a, 8b, 8c, 8d. In other embodiments, the LEDs lOa-lOd may be arranged in more than one linear array along the carrier 7a-7d. The LEDs 10a- lOd are configured to emit LED light.

[0187] The LED filament 2a, 2b, 2c, 2d further comprises an elongated encapsulant 15a, 15b, 15c, 15d that covers the LEDs lOa-lOd and the first side of the carrier 8a-8d. The elongated encapsulant 15a-15d may comprise a luminescent material that is configured to convert at least a part of the LED light emitted by the LEDs 10a- lOd into a converted light. Converted light may have a different wavelength, and color, than light that is not converted. Specifically, a luminescent material may absorb light at a first wavelength and re-emit the absorbed energy as light of a different wavelength.

[0188] Figure 2c illustrates a cross section of a LED filament arrangement, such as the LED filament arrangement 1 of Figure 1. The LED filament arrangement comprises a first LED filament 2a, a second LED filament 2b, a third LED filament 2c, and (optionally) a fourth LED filament 2d. The LED filaments 2a-2d may be equivalent to the LED filaments 2a-2d described with reference to Figures 2a and 2b, except in that the encapsulant 15a, 15b, 15c, 15d covers both the first major surface, on which the LEDs lOa-d are arranged, and the second major surface of each carrier 7a, 7b, 7c, 7d.2024PF80090

[0189] 22

[0190] In Figure 2c, the radial direction r extends to the left, and a longitudinal direction L extends in parallel with the central axis of the LED filament arrangement. Thus, the first LED filament 2a is arranged furthest, of the LED filaments 2a, 2b, 2c, 2d, from a center axis of a LED filament arrangement. The LED filaments 2a-2d are arranged such that the first major surface and the second major surface of the carriers 7a-7d are parallel with the longitudinal direction L.

[0191] The first LED filament 2a is arranged such that the first major surface, on which the LEDs 10a are arranged, faces outwards of the spiral shape, i.e., away from the central axis of the LED filament arrangement. The second, third and fourth LED filaments 2b-2d, are all arranged such that the first major surface, on which the LEDs lOb-d are arranged, faces into the spiral shape, i.e., towards the central axis of the LED filament arrangement.

[0192] With reference to Figures 3a and 3b, a LED filament arrangement comprising pairs of LED filaments sharing common elongated carrier will be described.

[0193] Figure 3a illustrates a side view of a section of a pair of LED filaments 2a’, 2b’ which share a common elongated carrier 23a. A common elongated carrier may be referred to as a common carrier. In Figure 3a, the section of the pair of LED filaments 2a’, 2b’, is illustrated as straight, although it is to be understood that, when mounted in an LED filament arrangement, such as a LED filament arrangement 1 of Figure la, the pair of LED filaments may be arranged so as to form at least a portion of a spiral shape. To illustrate the concept of a common carrier, a pair of LED filaments comprising the first LED filament 2a’ and the second LED filament 2b’ is used. However, it is to be understood that, similarly, the second and the third LED filaments may share a common carrier, or the third and fourth LED filaments may share a common carrier.

[0194] The first LED filament 2a’ and the second LED filament 2b’ may be equivalent to the first LED filament 2a and the second LED filament 2b described above with reference to previous figures except in that they share a common carrier 23a. Specifically, a first side, or portion, of the common carrier 23a forms the first carrier 7a’. A second side, or portion, of the common carrier 23a forms the second carrier 7b’. The first plurality of LEDs 10a’ is arranged on the first carrier 7a’. The first elongated encapsulant 15a’ covers the first plurality of LEDs 10a’ and the first carrier 7a’. The second plurality of LEDs 10b’ is arranged on the second carrier 7b’. The second elongated encapsulant 15b’ covers the second plurality of LEDs 10b’ and the second carrier 7b’.2024PF80090

[0195] 23

[0196] Figure 3b illustrates a cross-section of a LED filament arrangement. The LED filament arrangement illustrated in Figure 3b may be equivalent to the LED filament arrangement illustrated in Figure 2c, except in that the first and second LED filaments 2a’, 2b’, share a first common carrier 23a, and the third and fourth LED filaments 2c’, 2d’ share a second common carrier 23b. The first common carrier 23a and / or the second common carrier 23b of Figure 3b may be equivalent to the common carrier 23 a described with reference to Figure 3 a.

[0197] The first common carrier 23a comprises the first carrier 7a’ of the first LED filament 2a’ and the second carrier 7b’ of the second LED filament 2b’. The first common carrier 23a may be formed as a single unit comprising the first carrier 7a’ and the second carrier 7b’. Alternatively, the first common carrier 23a may be formed by the first carrier 7a’ being positioned adjacently to and / or abutting the second carrier 7b’.

[0198] The first LED filament 2a’ comprises LEDs 10a’, positioned on a major surface of the first carrier 7a’, i.e., on a first, radially outer, surface of the first common carrier 23a. The first LED filament 2a’ comprises an elongated encapsulant 15a’, covering at least a portion of the surface of the first carrier 7a’, and at least a portion of the LEDs 10a’ positioned on the first carrier 7a’.

[0199] The second LED filament 2b’ comprises LEDs 10b’, positioned on a major surface of the second carrier 7b’, i.e., on a second, radially inner, surface of the first common carrier 23a. The second LED filament 2b’ comprises an elongated encapsulant 15b’, covering at least a portion of the surface of the second carrier 7b’, and at least a portion of the LEDs 10b’ positioned on the second carrier 7b’.

[0200] The second common carrier 23b comprises the third carrier 7c’ of the third LED filament 2c’ and the fourth carrier 7d’ of the fourth LED filament 2d’. The second common carrier 23a may be formed as a single unit comprising the third carrier 7c’ and the fourth carrier 7d’. Alternatively, the second common carrier 23b may be formed by the third carrier 7c’ being positioned adjacently to and / or abutting the fourth carrier 7d’.

[0201] The third LED filament 2c’ comprises LEDs 10c’, positioned on a major surface of the third carrier 7c’, i.e., on a first, radially outer, surface of the second common carrier 23b. The third LED filament 2c’ comprises an elongated encapsulant 15c’, covering at least a portion of the surface of the third carrier 7c’, and at least a portion of the LEDs 10c’ positioned on the third carrier 7c’.

[0202] The fourth LED filament 2d’ comprises LEDs 10d’, positioned on a major surface of the fourth carrier 7d’, i.e., on a second, radially inner, surface of the second2024PF80090

[0203] 24

[0204] common carrier 23b. The fourth LED filament 2b’ comprises an elongated encapsulant 15d’, covering at least a portion of the surface of the fourth carrier 7d’, and at least a portion of the LEDs 10d’ positioned on the fourth carrier 7d’.

[0205] With reference to Figure 4, a LED filament arrangement 1 will be further described.

[0206] Figure 4 illustrates a LED filament arrangement 1, which may have several features in common with the LED filament arrangement 1 of Figure la. Hence, it is referred to the associated text for an increased understanding of these features.

[0207] In Figure 4, a portion of the LED filament arrangement 1 is illustrated in an exploded view. In the exploded view of Figure 4, a portion of each LED filament 2a-2d is presented in a cutaway view, i.e., without an elongated encapsulant 15a-15d, allowing visibility of the carriers 7a-7d and the LEDs lOb-lOd. Each elongated encapsulant 15a-15d may, however, cover the entire respective carrier 7a-7d.

[0208] Each LED filament 2a- 2d comprises a respective carrier 7a-7d. In Figure 4, as in Figure 2c, the first LED filament 2a is arranged such that the second major surface 9a is arranged inwards, i.e., facing the center axis A. Thus, the LEDs (10a, illustrated in e.g., Fig 2c) are arranged on a radially outer surface of the carrier 7a. The second, third and (optional) fourth LED filaments 2b, 2c, 2d are arranged such that the first major surface, on which the respective pluralities of LEDs are arranged, are arranged inwards, facing the central axis.

[0209] Each LED filament 2a, 2b, 2c, 2d is arranged to emit LED filament light 3a, 3b, 3c, 3d. The LED filaments 2a2d are illustrated as emitting light 3a-3d both radially inwards and radially outwards. The carriers 7a-7d of the LED filaments 2a-2d may be at least partially transmissive to light emitted by the LEDs, and potentially converted by a luminescent material in an encapsulant 15a-d. However, one or more of the carriers 7a-7d may have a reflectivity of at least 70%, or at least 80%, or at least 85% for visible light. The LED filaments 2a, 2b, 2c, 2d may be arranged to emit a majority of light in a certain direction, such as away from a center axis, along a center axis, or towards a center axis.

[0210] Specifically, the arrangement of the first LED filament 2a, in which the LEDs are arranged on a radially outer surface of the carrier, may provide that more than 50%, or more than 60%, such as at least 70% of the first LED filament light 3a is directed away from the center axis A. The arrangement of the innermost fourth LED filament 2d, in which the LEDs are arranged on a radially inner surface of the carrier, may provide that the more than 50%, or more than 60%, such as at least 70% of the fourth LED filament light 3d is directed into the spiral shape, in directions generally toward the central axis A. The second and third LED2024PF80090

[0211] 25

[0212] filament light 3b, 3c may be partially blocked by the carriers 7a, 7b, 7c, 7d of adjacent LED filaments. At least 50%, or more than 60%, such as at least 70% of the second and third LED filament light 3b, 3c may be emitted in directions generally along the center axis A, such as in directions deviating up to 15 degrees from the center axis A.

[0213] Figure 5 illustrates a LED filament arrangement 1 from a top-down view. The LED filament arrangement 1 of Figure 5 may have several features in common with the LED filament arrangement 1 of Figure la, Figure lb, and / or Figure 4. Hence, it is referred to the associated text relating to Figure la, Figure lb, and / or Figure 4 for an increased understanding of these features.

[0214] Figure 5 illustrates LED filaments 2a, 2b, 2c, 2d with a respective first endpoint Ila, 11b, 11c, lid and a respective second endpoint 12a, 12b, 12c, 12d. Each LED filament 2a-2d is arranged so as to have the shape of a spiral arranged concentrically around a center axis A, with a start of the spiral at the first endpoint 1 la-1 Id and an end of the spiral at a second endpoint 12a-12d. Between the first endpoint Ila- lid and the respective second endpoint 12a- 12d, each respective LED filament 2a- 2d forms at least one full turn around the center axis A. Preferably, the LED filaments 2a2d are arranged so as to form several turns around the center axis A.

[0215] Figure 5 illustrates a first line 13, extending, from the center axis A, along a radial axis. The first endpoints 1 la-1 Id are aligned along the first line 13. Figure 5 illustrates a second line 14, extending, from the center axis A, along a radial axis. The first line 13 and the second line 14 are illustrated as having a non-zero angle relative to each other, however, the first line 13 and the second line 14 may be parallel. The second endpoints 12a-12d are aligned along the second line 14. In order to align the endpoints 1 la-d, 12a-d, the LED filaments 2a-2d are of different lengths, as compared to each other. More specifically, the first LED filament 2a is radially further out and therefore also the longest of the LED filaments 2a-2d. The second LED filament 2b is longer than the third LED filament 2c, and the third LED filament 2c is longer than the fourth LED filament 2d.

[0216] The support structure 17 has supporting elements 25, extending from the center axis A, connected to the first endpoints 1 la-1 Id and the second endpoint 12a-12d.

[0217] Figures 6a and 6b illustrate cross-sections of a LED filament arrangement comprising LED filaments 2a, 2b, 2c, 2d. The LED filament arrangement illustrated in Figure 6a and 6b may be equivalent to the LED filament arrangements 1 described above with reference to preceding figures.2024PF80090

[0218] 26

[0219] The first LED filament 2a, the second LED filament 2b, the third LED filament 2c, and the fourth LED filament 2d are configured to emit light of colors which are different from each other. More specifically, a first color of the first LED filament light, a second color of the second LED filament light, a third color of the third LED filament light, and a fourth color of the fourth LED filament light are different from each other.

[0220] The LED filaments 2a, 2b, 2c, 2d of Figure 6a are affixed to one another by an adhesive material 16. The first LED filament 2a is affixed to the second LED filament 2b. The second LED filament 2b is affixed to the third LED filament 2c. The third LED filament 2c is affixed to the fourth LED filament 2d.

[0221] The LED filaments 2a, 2b, 2c, 2d of Figure 6b are affixed to one another by a holder 20. Specifically, the holder 20 comprises one through hole or aperture for each LED filament 2a-2d. In an alternative embodiment, not illustrated, the LED filaments 2a, 2b, 2c, 2d may be affixed by a combination of adhesive 16 and one or more holders 20.

[0222] Figure 7 illustrates a lamp or a luminaire 22 comprising a LED filament arrangement 1 according to any embodiment of the present disclosure. The lamp or luminaire 22 further comprises a casing 24 that is at least partially transmissive to LED filament arrangement light and at least partially encloses the LED filament arrangement 1.

[0223] 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.

[0224] Although features and elements are described above in particular combinations, each feature or element can be used alone without the other features and elements or in various combinations with or without other features and elements.

[0225] 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, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage.

Claims

2024PF8009027CLAIMS:

1. A light-emitting diode, LED, filament arrangement (1) configured to, in operation, emit LED filament arrangement light (3), the LED filament arrangement comprising:a first LED filament (2a) configured to emit first LED filament light (3a) of a first color, the first LED filament having the shape of a spiral having a first diameter (4a), the first LED filament comprising an array of a plurality of first LEDs (10a) arranged on a first elongated carrier (7a);a second LED filament (2b) configured to emit second LED filament light (3b) of a second color, the second filament having the shape of a spiral having a second diameter (4b), the second LED filament comprising an array of a plurality of second LEDs (10b) arranged on a second elongated carrier (7b); anda third LED filament (2c) configured to emit third LED filament light (3c) of a third color, the third LED filament having the shape of a spiral having a third diameter (4c), the third LED filament comprising an array of a plurality of third LEDs (10c) arranged on a third elongated carrier (7c);wherein the first color is different from the second color;wherein the first color is different from the third color;wherein the second color is different from the third color;wherein the second diameter (4b) is smaller than the first diameter (4a); wherein the third diameter (4c) is smaller than the second diameter (4b); and wherein the first LED filament (2a), the second LED filament (2b), and the third LED filament (2c) are arranged concentrically around a center axis (A) of the LED filament arrangement (1), and the first LED filament (2a), the second LED filament (2b), and the third LED filament (2c) are stacked in a stack in a radial direction (6) in relation to the center axis (A).

2. The LED filament arrangement (1) according to claim 1, further comprising:a fourth LED filament (2d) configured to emit fourth LED filament light (3d) of a fourth color, the fourth LED filament having the shape of a spiral having a fourth2024PF8009028diameter (4d), the fourth LED filament comprising an array of a plurality of fourth LEDs (lOd) arranged on a fourth elongated carrier (7d);wherein the fourth color is different from the first color, the second color, and the third color,wherein the fourth diameter (4d) is smaller than the third diameter (4c); and wherein the first LED filament (2a), second LED filament (2b), the third LED filament (2c), and the fourth LED filament (2d) are arranged concentrically around the center axis (5) of the LED filament arrangement (1), and the first LED filament (2a), the second LED filament (2b), the third LED filament (2c), and the fourth LED filament (2d) are stacked in a stack in the radial direction (6) in relation to the center axis (A).

3. The LED filament arrangement (1) according to claim 2, wherein one of the LED filaments is configured to emit white light having a correlated color temperature in a range from 1700K to 6500K and a color rendering index of at least 80, wherein another one of the LED filaments is configured to emit red light, wherein yet another one of the LED filaments is configured to emit green light, and wherein still another one of the LED filaments is configured to emit blue light.

4. The LED filament arrangement (1) according to any one of the preceding claims, wherein the stack of the first LED filament, the second LED filament, the third LED filament and, when provided, the fourth LED filament has a stack thickness, ST, and a stack width, SW, wherein ST / SW>2.

5. The LED filament arrangement (1) according to any one of the preceding claims, wherein the first LED filament (2a) is configured to emit white light having a correlated color temperature in a range from 1700K to 6500K and a color rendering index of at least 80.

6. The LED filament arrangement (1) according to any one of the preceding claims, wherein a LED filament (2c, 2d) that is arranged the closest to the center axis (A) is configured to emit blue light (3c, 3d).

7. The LED filament arrangement (1) according to any one of the preceding claims, wherein a LED filament (2b, 2c) that is arranged between the first LED filament (2a)2024PF8009029and a LED filament (2c, 2d) that is arranged the closest to the center axis (A) is configured to emit red light (3b, 3c).

8. The LED filament arrangement (1) according to any one of the preceding claims, wherein the first LED filament (2a) is configured to emit more than 50% of the first LED filament light (3a) away from the center axis (A).

9. The LED filament arrangement (1) according to any one of the preceding claims, wherein the LED filament (2c, 2d) that is arranged the closest to the center axis (5) is configured to emit more than 50% of its emitted light (3c, 3d) in directions towards the center axis (A).

10. The LED filament arrangement (1) according to any one of the preceding claims, wherein a LED filament (2b, 2c) that is arranged between the first LED filament (2a) and the LED filament (2c, 2d) that is arranged the closest to the center axis (5) is configured to emit more than 50% of its emitted light (3b, 3c) in a direction along the center axis (A).

11. The LED filament arrangement (1) according to any one of the preceding claims, wherein the elongated carriers of at least two of the LED filaments have a reflectivity of at least 70% for visible light.

12. The LED filament arrangement (1) according to any one of the preceding claims, wherein the LED filaments (2a, 2b, 2c, 2d) are affixed one to each other by an adhesive material (16) or by one or more holders.

13. The LED filament arrangement (1) according to any one of the preceding claims, comprising a common elongated carrier (23a, 23b), wherein the common elongated carrier comprises (i) the first and the second elongated carriers, or (ii) the second and the third elongated carriers, or, if applicable, (iii) the third and the fourth elongated carriers.

14. The LED filament arrangement (1) according to any one of the preceding claims, wherein two or more of the following applies:the first LED filament (2a) comprises a first elongated encapsulant (15a) at least partly covering the first elongated carrier and at least partly enclosing the plurality of2024PF8009030first LEDs, wherein the first elongated encapsulant comprises a first luminescent material configured to at least partly convert a first LED light emitted by the plurality of first LEDs into a first converted light;the second LED filament (2b) comprises a second elongated encapsulant (15b) at least partly covering the second elongated carrier and at least partly enclosing the plurality of second LEDs, wherein the second elongated encapsulant comprises a second luminescent material configured to at least partly convert a second LED light emitted by the plurality of second LEDs into a second converted light;the third LED filament (2c) comprises a third elongated encapsulant (15c) at least partly covering the third elongated carrier and at least partly enclosing the plurality of third LEDs, wherein the third elongated encapsulant comprises a third luminescent material configured to at least partly convert a third LED light emitted by the plurality of third LEDs into a third converted light; andwhen provided, the fourth LED filament (2d) comprises a fourth elongated encapsulant at least partly covering the fourth elongated carrier and at least partly enclosing the plurality of fourth LEDs, wherein the fourth elongated encapsulant comprises a fourth luminescent material configured to at least partly convert the fourth LED light emitted by the plurality of fourth LEDs into a fourth converted light.

15. A lamp or a luminaire (22) comprising an LED filament arrangement (1) according to any one of the preceding claims and a casing (24) that is at least partially transmissive to LED filament arrangement light.

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