Optical and thermal improvements of double-sided multichannel filaments.

Abstract

The present invention provides an LED filament device 1000 comprising: (i) a first LED filament surface 1110; (ii) a second LED filament surface 1120; (iii) an intermediate layer 440; and (iv) a plurality of light sources 100, wherein: (a) the first light source 110 is configured to generate a first white light 111 having a first correlated color temperature CCT1, the first light source 110 being associated with the first filament surface 1110; (b) the second light source 120 is configured to generate a second white light 121 having a second correlated color temperature CCT2, the second light source 120 being associated with the first filament surface 1110, CCT2-CCT1≧500K; and (c) the third light source 130 is configured to generate a blue third light 131, the third light source 130 being associated with the first filament surface 1110, CCT2-CCT1≧500K. 130 is associated with the second filament surface 1120, (d) a fourth light source 140 is configured to generate a green fourth light 141, the fourth light source 140 is associated with the second filament surface 1120, (e) a fifth light source 150 is configured to generate a red fifth light 151, the fifth light source 150 is associated with the second filament surface 1120, (1) the intermediate layer 440 comprises a thermally conductive element 450, (g) the first LED filament surface 1110, the second LED filament surface 1120, and (iii) the intermediate layer 440 are comprised by a sandwich configuration 400, the intermediate layer 440 being configured between at least a portion of the first LED filament surface 1110 and at least a portion of the second LED filament surface 1120.

Description

[Technical field]

[0001] The present invention relates to a device and to a retrofit lamp or other lighting device comprising such a device. The present invention also relates to an LED filament device for such a device. [Background technology]

[0002] LED filament lamps are known in the art. For example, US Patent Application Publication No. 2018 / 0328543 describes a lamp comprising an optically transparent enclosure for emitting emitted light, a base connected to the enclosure, at least one first LED filament and at least one second LED filament in the enclosure operable to emit light when energized via an electrical path from the base, the at least one first LED filament emitting light having a first correlated color temperature (CCT) and the at least one second LED filament emitting light having a second CCT, the at least one first LED filament and at least one second LED filament combined to generate the emitted light, and a controller that changes the CCT of the emitted light when the lamp is dimmed. The optically transparent enclosure is transparent.

[0003] Incandescent lamps are being rapidly replaced by LED-based lighting solutions. Nevertheless, it may be appreciated and desired by users to have a retrofit lamp with the appearance of an incandescent bulb. For this purpose, the infrastructure for manufacturing glass-based incandescent lamps may be utilized to replace the filament with an LED that emits white light. One of the concepts is based on an LED filament that is placed in such a bulb. The appearance of these lamps is highly valued due to their decorative appearance. Summary of the Invention [Problem to be solved by the invention]

[0004] Current LED filament lamps are not color controllable. To produce color controllable LED filament lamps, RGB LEDs on a (e.g., translucent or transparent) substrate can be utilized. However, such configurations may not result in a pleasing appearance. Other LED filament lamps may be color controllable but may have a relatively off-white color. Additionally, LED filaments may have maintenance and / or stability issues at relatively high powers. [Means for solving the problem]

[0005] Therefore, one aspect of the present invention is to provide an alternative light generating device, which preferably also at least partially obviates one or more of the above-mentioned drawbacks. The present invention may have as an object to overcome or ameliorate at least one of the drawbacks of the prior art, or to provide a useful alternative. The present invention may have as an object to provide an LED filament with improved performance (e.g., in terms of color and correlated color temperature control) and a pleasing appearance.

[0006] In one aspect, the present invention provides an LED filament device comprising: (i) a first LED filament surface; (ii) a second LED filament surface; (iii) an intermediate layer; and (iv) a plurality of light sources. The plurality of light sources may comprise a first light source, a second light source, a third light source, a fourth light source, and a fifth light source. In particular, the first light source may be configured to generate a first white light having a first correlated color temperature CCT1. In particular, in an embodiment, the first light source is associated with the first filament surface. Furthermore, in particular, the second light source may be configured to generate a second white light having a second correlated color temperature CCT2. In particular, in an embodiment, the second light source is associated with the first filament surface. In a particular embodiment, CCT2-CCT1≧500K. Still further, in particular, the third light source may be configured to generate a blue third light. In particular, in an embodiment, the third light source is associated with the second filament surface. Still further, in particular the fourth light source may be configured to generate a fourth light of green color. In particular, in an embodiment, the fourth light source is associated with the second filament surface. Furthermore, in particular the fifth light source may be configured to generate a fifth light of red color. In particular, in an embodiment, the fifth light source may be associated with the second filament surface. Furthermore, in particular the intermediate layer may comprise a thermally conductive element. Still further, in an embodiment, the first LED filament surface, the second LED filament surface, and (iii) the intermediate layer may be included by a sandwich configuration. In particular, the intermediate layer may be configured between at least a portion of the first LED filament surface and at least a portion of the second LED filament surface.Thus, in a particular embodiment, the present invention relates to an LED filament device comprising: (i) a first LED filament surface; (ii) a second LED filament surface; (iii) an intermediate layer; and (iv) a plurality of light sources, wherein: (a) the first light source is configured to generate a first white light having a first correlated color temperature CCT1, the first light source being associated with the first filament surface; (b) the second light source is configured to generate a second white light having a second correlated color temperature CCT2, the second light source being associated with the first filament surface, CCT2-CCT1≧500K; and (c) the third light source is configured to generate a blue third light, the third light source being associated with the first filament surface, CCT2-CCT1≧500K. (a) a third light source is associated with the second filament surface, (b) a fourth light source is configured to generate a green fourth light, the fourth light source is associated with the second filament surface, (c) a fifth light source is configured to generate a red fifth light, the fifth light source is associated with the second filament surface, (d) a third light source is configured to generate a green fourth light, the fourth light source is associated with the second filament surface, (e) a fifth light source is configured to generate a red fifth light, the fifth light source is associated with the second filament surface, (f) the intermediate layer comprises a thermally conductive element, and (g) the first LED filament surface, the second LED filament surface, and (iii) the intermediate layer are comprised by a sandwich configuration, the intermediate layer being configured between at least a portion of the first LED filament surface and at least a portion of the second LED filament surface.

[0007] In the present invention, it may be possible to provide white light, which may have a relatively low correlated color temperature (CCT) in embodiments. Furthermore, in the present invention, it may be possible to provide colored light. Furthermore, the color point of the light may be controllable. Furthermore, the color point of the white light may be closer to the black body locus (BBL) and / or the color rendering index (CRI) may be higher. Furthermore, the present invention may provide visible light within a relatively large color gamut. Furthermore, the present invention may provide better thermal management, allowing for a longer life and / or better performance and reliability. Furthermore, the present invention may optimize color mixing. Furthermore, the present invention provides LED filaments (devices) with improved performance (e.g., in terms of color and correlated color temperature control) and pleasing appearance. The reason is that a first white light having a first correlated color temperature and a second white light having a second correlated color temperature are provided by (all of) the first light source and the second light source provided on the first filament surface, while a third light in blue, a fourth light in green, and a fifth light in red are provided by (all of) the third, fourth, and fifth light sources provided on the second filament surface. In this way, the different colors and the different (correlated) color temperatures are well mixed / distributed, while the LED filament has a pleasing appearance, for example, because it has a (relatively) thin, i.e. small diameter / width. The above-mentioned double-sided multi-channel filament provides optical and / or thermal improvements.

[0008] As described above, in an embodiment, the present invention provides an LED filament device comprising: (i) a first LED filament surface; (ii) a second LED filament surface; (iii) an intermediate layer; and (iv) a plurality of light sources.

[0009] In an embodiment, the present invention provides an LED filament device comprising an LED filament. In particular, the LED filament comprises a plurality of light sources. In an embodiment, the plurality of light sources comprises a first light source, a second light source, a third light source, a fourth light source, and a fifth light source. In operation, the LED filament device may provide a filament device light ("device light") that may include light from one or more of the light sources (of these types).

[0010] As mentioned above, the LED filament device is particularly configured to generate (during operation of the LED filament device) filament device light, which is particularly light that escapes from the LED filament device during operation of the LED filament device.

[0011] An LED filament device may comprise one or more LED filaments ("filaments"). The invention is generally further described in relation to a single filament. However, as will become apparent, there may be more than one filament. Thus, an LED filament device may, in certain embodiments, comprise multiple LED filaments. When there are more than one filament, they may (in embodiments) provide light having different optical properties or essentially the same optical properties during an operational mode.

[0012] If there are two or more LED filaments, the LED filaments may not necessarily be the same. For example, there may be two or more LED filaments with different numbers of solid-state light sources. Alternatively or additionally, there may be two or more LED filaments with different shapes. Alternatively or additionally, there may be two or more LED filaments configured to generate filament light with different spectral power distributions. Alternatively or additionally, there may be two or more LED filaments with different spectral power distribution tunability.

[0013] Furthermore, there may be a set of LED filaments, the set including two or more LED filaments, which may be essentially identical in number of solid-state light sources, filament light spectral power distribution, etc., and the LED filaments within a set are (and therefore) not essentially different from each other (in terms of filament light spectral power distribution), while LED filaments from different sets may differ from each other (particularly in filament light spectral power distribution).

[0014] As mentioned above, the present invention provides an LED filament device comprising an LED filament. In particular, the LED filament includes a plurality of light sources. In this specification, the term "light source" is used in embodiments when referring to a light source, such as a solid-state light source, where the light is used by itself, and in embodiments when referring to a combination of a light source, such as a solid-state light source, and a luminescent material, where at least the luminescent material light may also be used. Therefore, in certain embodiments, the term "light source" may refer to one or more of the following: (i) a solid-state light source, such as a direct LED; (ii) a phosphor-converted light source, such as a PC LED; and (iii) a combination of a solid-state light source and a luminescent material, such as one that may be available as a light-transmitting coating material, in which one or more solid-state light sources are embedded. Therefore, a plurality of light sources in particular includes a plurality of solid-state light sources. In certain embodiments, each light source may include a solid-state light source, such as an LED. Therefore, when referring hereinafter to the pitch of a light source, this may in particular refer to the pitch of the corresponding solid-state light source.

[0015] The term "light source" may in principle relate to any light source known in the art. In certain embodiments, the light source comprises a solid-state LED light source, such as an LED or a laser diode (or "diode laser"). The term "light source" may also relate to a plurality of light sources, such as 2 to 200 (solid-state) LED light sources. The term LED may therefore also refer to a plurality of LEDs. Furthermore, the term "light source" may also refer in embodiments to so-called chips-on-board (COB) light sources. The term "COB" in particular refers to an LED chip in the form of a semiconductor chip, which is mounted directly on a substrate, such as a PCB, without encapsulation or connection. Thus, several optical semiconductor light sources may be configured on the same substrate. In an embodiment, the COB is a multi-LED chip, which is configured together as a single lighting module.

[0016] A light source has a light exit surface. With reference to conventional light sources, such as light bulbs or fluorescent lamps, the light exit surface may be the outer surface of a glass or quartz envelope. With respect to LEDs, the light exit surface may for example be the LED die or the outer surface of the resin if the resin is applied to the LED die. In principle, the light exit surface may also be the end of a fiber. The term exit surface particularly relates to that part of a light source where the light actually leaves or exits from the light source. The light source is configured to provide a beam of light. This beam of light exits from the light exit surface of the light source.

[0017] The term "light source" may refer to a semiconductor light emitting device, such as a light emitting diode (LED), a resonant cavity light emitting diode (RCLED), a vertical cavity laser diode (VCSEL), an edge-emitting laser, etc. The term "light source" may also refer to an organic light emitting diode, such as a passive-matrix organic light-emitting diode (PMOLED) or an active-matrix organic light-emitting diode (AMOLED). In certain embodiments, the light source includes a solid-state light source (such as an LED or a laser diode). In one embodiment, the light source includes an LED (light emitting diode). The term "light source" or "solid-state light source" may also refer to a superluminescent diode (SLED).

[0018] The term LED may also refer to multiple LEDs. Furthermore, the term "light source" may also refer in embodiments to so-called chips-on-board (COB) light sources. The term "COB" refers in particular to an LED chip in the form of a semiconductor chip that is mounted directly on a substrate, such as a PCB, without encapsulation or connection. Thus, multiple semiconductor light sources may be configured on the same substrate. In an embodiment, the COB is a multi-LED chip that is configured together as a single lighting module.

[0019] The term "light source" may also refer to multiple (essentially identical (or different)) light sources, such as 2-2000 solid-state light sources. In embodiments, the light source may include one or more micro-optical elements (array of microlenses) downstream of a single solid-state light source, such as an LED, or downstream of multiple solid-state light sources (i.e., shared, for example, by multiple LEDs). In embodiments, the light source may include an LED with on-chip optical elements. In embodiments, the light source includes a pixelated single LED (with or without optical elements) (which, in embodiments, provides on-chip beam steering).

[0020] The terms "upstream" and "downstream" refer to the location of an article or feature relative to the propagation of light from a light generating means (here specifically a light source), where relative to a first location in the light beam from the light generating means, a second location in the light beam that is closer to the light generating means is "upstream" and a third location in the light beam that is farther away from the light generating means is "downstream".

[0021] In an embodiment, the light source may be configured to provide a primary radiation to be used on its own, for example a blue light source such as a blue LED, or a green light source such as a green LED, and a red light source such as a red LED. Such LEDs, which may not include a luminescent material ("phosphor"), may be directly referred to as color LEDs.

[0022] However, in other embodiments, the light source may be configured to provide a primary radiation, and (at least) a portion of the primary radiation is converted to a secondary radiation. The secondary radiation may be based on conversion by a luminescent material. Hence, the secondary radiation may also be denoted as luminescent material radiation. The luminescent material may be included by the light source, in embodiments, such as an LED having a luminescent material layer or a dome containing the luminescent material. Such an LED may be denoted as a phosphor-converted LED or a PC LED. In other embodiments, the luminescent material may be configured at some distance ("remote") from the light source, such as an LED having a luminescent material layer that is not in physical contact with the die of the LED. Thus, in certain embodiments, the light source may be a light source that emits light in operation at a wavelength selected from at least the range of 380-470 nm. However, other wavelengths may also be possible. This light may be used in part by the (optional) luminescent material.

[0023] In an embodiment, the light source may be selected from the group of laser diodes and superluminescent LEDs, hi other embodiments, the light source comprises an LED.

[0024] The term "laser source" refers in particular to a laser. Such a laser may be configured in particular to generate laser source light having one or more wavelengths in the UV, visible or infrared, in particular having a wavelength selected from the spectral wavelength range of 200-2000 nm, for example 300-1500 nm. The term "laser" refers in particular to a device that emits light through a process of light amplification based on stimulated emission of electromagnetic radiation. In particular, in embodiments, the term "laser" may refer to a solid-state laser. In certain embodiments, the term "laser" or "laser source" or similar terms refer to a laser diode (or diode laser).

[0025] Thus, in an embodiment, the light source comprises a laser light source. In an embodiment, the term "laser" or "solid-state laser" refers to a laser such as a cerium-doped lithium strontium (or calcium) aluminum fluoride (Ce:LiSAF, Ce:LiCAF), a chromium-doped chrysoberyl (alexandrite) laser, a chromium-ZnSe (Cr:ZnSe) laser, a divalent samarium-doped calcium fluoride (Sm:CaF2) laser, an Er:YAG laser, an erbium-doped and an erbium-ytterbium co-doped glass laser, F-center laser, Holmium YAG (Ho:Nd:YAG) laser, Nd:YAG laser, NdCrYAG laser, Neodymium-doped yttrium calcium oxoborate Nd:YCa4O(BO3)3 or Nd:YCOB, Neodymium-doped yttrium orthovanadate (Nd:YVO4) laser, Neodymium-glass (Nd:glass) laser, Neodymium YLF (Nd:YLF) solid-state laser, Promethium-147-doped phosphate glass (147 Pm 3+ : Glass) solid-state laser, ruby ​​laser (Al2O3:Cr 3+ ), thulium YAG (Tm:YAG) laser, titanium sapphire (Ti:sapphire; Al2O3:Ti 3+ ) lasers, trivalent uranyl doped calcium fluoride (U:CaF2) solid-state lasers, ytterbium doped glass lasers (rod, plate / chip, and fiber), ytterbium YAG (Yb:YAG) lasers, Yb2O3 (glass or ceramics) lasers, etc.

[0026] In embodiments, the term "laser" or "solid state laser" may refer to one or more of semiconductor laser diodes, such as GaN, InGaN, AlGaInP, AlGaAs, InGaAsP, lead-salt, vertical cavity surface emitting lasers (VCSELs), quantum cascade lasers, hybrid silicon lasers, and the like.

[0027] The laser may be combined with an upconverter to reach shorter (laser) wavelengths. For example, the upconversion may be obtained by some (trivalent) rare earth ions or the upconversion can be obtained by nonlinear crystals. Alternatively, the laser may be combined with a downconverter, such as a dye laser, to reach longer (laser) wavelengths.

[0028] As can be derived from the following, the term "laser light source" may also refer to a plurality of (different or identical) laser light sources. In certain embodiments, the term "laser light source" may refer to a plurality N of (identical) laser light sources. In an embodiment, N=2 or more. In certain embodiments, N may be at least 5, such as in particular at least 8. In this way, a higher brightness may be obtained. In an embodiment, the laser light sources may be arranged in a laser bank (see also above). The laser bank may in an embodiment include a heat sink and / or optical elements, for example lenses for collimating the laser light.

[0029] The laser source is configured to generate laser source light (or "laser light"). The source light may consist essentially of laser source light. The source light may also include laser source light of two or more (different or the same) laser sources. For example, the laser source light of two or more (different or the same) laser sources may be coupled into a light guide to provide a single light beam including the laser source light of two or more (different or the same) laser sources. Thus, in certain embodiments, the source light is in particular a collimated source light. In yet further embodiments, the source light is in particular a (collimated) laser source light.

[0030] The phrases "different light sources" or "multiple different light sources" and similar phrases may, in embodiments, refer to multiple solid-state light sources selected from at least two different bins. Similarly, the phrases "same light source" or "multiple identical light sources" and similar phrases may, in embodiments, refer to multiple solid-state light sources selected from the same bin.

[0031] The filament may include a support and a solid-state light source supported by the support. In particular, the filament may include a (light-transmissive) encapsulant that may at least partially surround the solid-state light source, in particular at least surround the light-emitting surface of the solid-state light source, such as a die.

[0032] The LED filament may, in an embodiment, include a support, a set of solid-state light sources ("light sources"), and an encapsulant. The LED filament may have a length axis having a first length (L1). In particular, the solid-state light sources are disposed on the support over the first length (L1) of the LED filament. Furthermore, the solid-state light sources are configured to generate source light (during operation of the light-generating device). In particular, in an embodiment, the encapsulant surrounds at least a portion of each of the solid-state light sources of the set of solid-state light sources. In general, the filament may have an aspect ratio of length to width and an aspect ratio of length to height of at least 10, for example selected from the range of 10 to 10,000. The aspect ratios of different filaments may be different in certain embodiments, but in embodiments, the aspect ratios may be essentially the same. It is noted that the aspect ratios of length to width and length to height of the filaments may be different.

[0033] The support may, in embodiments, include one or more of (metal) leads and resin (materials). In certain embodiments, the support may include a flexible PCB. In certain embodiments, the support may include a polymer support, such as a polyimide support. In certain embodiments, the support may include a light-transmitting polymer support. The support may be flexible. In embodiments, the support may include a foil.

[0034] Further, in embodiments, the encapsulant may include a luminescent material configured to convert at least a portion of the source light into luminescent material light. Alternatively or additionally, one or more of the one or more solid state light sources may include a luminescent material, and the encapsulant may be transparent or translucent in embodiments.

[0035] Further alternatively or additionally, the solid state light source may be configured to generate solid state light source light without having a conversion material included by the solid state light source, i.e., the solid state light source light may have essentially the same spectral power distribution as that exiting the die, and even in such embodiments, the (optional) encapsulant may be transparent or translucent in embodiments.

[0036] In particular, the filament may be configured to generate filament light (during the corresponding filament mode of operation). The filament light may include one or more of luminescent material light and solid-state light source light (for solid-state light sources without luminescent material). The luminescent material light may be from a PC solid-state light source, i.e., a phosphor converter solid-state light source, or from a luminescent material in an encapsulant. A solid-state light source without luminescent material may also be referred to herein as a non-PC solid-state light source or a direct color LED.

[0037] As described above, the LED filament device may include an LED filament, which includes a support, a set of solid-state light sources, and an encapsulant.

[0038] The number of (solid state) light sources in the LED filament may be at least 20, such as at least 24, such as at least 40, such as at least 48, such as up to 100 or even more. In particular, in an embodiment, the number of (solid state) light sources in the set may be selected from the range of 20 to 1000, such as 10 to 200.

[0039] Thus, in embodiments, the one or more light sources may each include a solid-state light source. Alternatively or additionally, in embodiments, the one or more light sources may each include a solid-state light source having a luminescent material, i.e., in embodiments, a PC LED.

[0040] In particular, in an embodiment there are at least five different light sources that may be used to generate light with different spectral power distributions. Thus, in an embodiment a plurality of light sources may be available, comprising a first light source, a second light source, a third light source, a fourth light source and a fifth light source. In particular, the invention is described in relation to a first light source, a second light source, a third light source, a fourth light source and a fifth light source. However, other embodiments with more or fewer light sources or different combinations of light sources may also be possible (see also below).

[0041] Herein, inter alia, two main embodiments may be available. In a series of embodiments, two LED filaments may be applied, which may be associated with each other, in particular with a solid-state light source on a single face of each LED filament. Thus, a sandwich configuration may be provided, which in an embodiment may comprise a first LED filament and a second LED filament, optionally with an intermediate layer between them. One filament may provide a first filament face, and the other filament may provide a second filament face. In this way, a sandwich configuration may be provided, with the first filament face and the second filament face providing the upper face or upper side of the sandwich configuration, and the lower face or lower side of the sandwich configuration. In another series of embodiments, a single LED filament may be applied, with all solid-state light sources generally on one face, which may be folded to provide a folded filament, optionally with an intermediate layer between them. One part of the filament may provide a first filament face, and the other part of the filament, opposite the one part, may provide a second filament face. Also in this manner, a sandwich configuration may be provided, with the first filament surface and the second filament surface providing a top surface or upper side and a bottom surface or lower side of the sandwich configuration.

[0042] Instead of the term sandwich configuration, the term sandwich LED filament may also be used. The sandwich may in particular be defined by a single LED filament (folded into a sandwich configuration) or by two LED filaments (configured in a sandwich configuration). The sandwich configuration may thus comprise a first filament surface on one side and a second filament surface on another side.

[0043] In particular, the light source may be configured with an array of 2-3 rows on a first filament face and an array of 2-3 rows on a second filament face, which may allow for thinner filaments that may be more flexible and / or easier to manufacture and / or apply.

[0044] In particular, a first LED filament surface may be provided with a warm white and a cold white light source and a second LED filament surface may be provided with an RGB light source, however other embodiments may also be possible.

[0045] The term "white light" in this specification is known to those skilled in the art. White light particularly relates to light having a correlated color temperature (CCT) in the range of about 1800-20000K, such as 2000-20000K, particularly 2700-20000K, particularly about 2700K-6500K for general lighting. In embodiments, for backlighting purposes, the correlated color temperature (CCT) may particularly be in the range of about 7000K-20000K. Furthermore, in embodiments, the correlated color temperature (CCT) is particularly within about 15 SDCM (standard deviation of color matching) from the black body locus (BBL), particularly within about 10 SDCM from the BBL, even more particularly within about 5 SDCM from the BBL.

[0046] In particular, the first light source may be configured to generate a first white light having a first correlated color temperature CCT1. Furthermore, the first light source is associated with the first filament surface. Thus, the first light source may be operatively coupled to the first filament surface. In particular, the second light source may be configured to generate a second white light having a second correlated color temperature CCT2. Thus, in an embodiment, the spectral power distributions of the first white light and the second white light are different. Furthermore, the second light source is associated with the first filament surface. Thus, the second light source may be (as well) operatively coupled to the first filament surface.

[0047] In particular, the first light source provides a warmer white color and the second light source provides a cooler light. Thus, in an embodiment, CCT2-CCT1≧500K. In a particular embodiment, CCT1 may be selected from a range of up to 2400K, and in a particular embodiment, CCT2 may be selected from a range of at least 2300K, for example, in particular at least 2700K. In particular, in an embodiment, CCT2-CCT1≧500K may apply. In an embodiment, CCT1 may be selected from a range of up to 2400K, and CCT2 may be selected from a range of at least 2700K. In a further particular embodiment, CCT2 may be at least 3000K, for example at least 3500K. Even more particularly, CCT2 is at least 4000K. In an embodiment, CCT2 may be selected from a range of 2700-4000K. In a particular embodiment, CCT1 is selected from the range of 1700-2400K, for example from the range of 1900-2300K, and CCT2 is selected from the range of 2500-6500K, for example from the range of 3000-4500K. In particular, in an embodiment, CCT2-CCT1≧1000K. In a particular embodiment, CCT1 is selected from the range of up to 1900-2400K, and CCT2 is selected from the range of 2700-6500K, and CCT2-CCT1≧1000K. Even more particularly, in an embodiment, CCT2-CCT1≧2000K. This may allow a relatively large tunability of the CCT.

[0048] Furthermore, in particular, the third light source may be configured to generate a blue third light. In an embodiment, the third light source is associated with the second filament surface. Thus, the third light source may be operatively coupled to the second filament surface. In particular, a majority of all the third light sources are associated with the second filament surface. More particularly, at least 90% of the total number of all the third light sources are associated with the second filament surface. Even more particularly, all the third light sources are associated with the second filament surface.

[0049] Furthermore, in particular the fourth light source may be configured to generate a green fourth light. In an embodiment, the fourth light source is associated with the second filament surface. Thus, the fourth light source may be operatively coupled to the second filament surface. In particular, a majority of all fourth light sources are associated with the second filament surface. More particularly, at least 90% of the total number of all fourth light sources are associated with the second filament surface. Even more particularly, all fourth light sources are associated with the second filament surface.

[0050] Furthermore, in particular the fifth light source may be configured to generate a red fifth light. In an embodiment, the fifth light source is associated with the second filament surface. Thus, the fifth light source may be operatively coupled to the second filament surface. In particular, a majority of all fifth light sources are associated with the second filament surface. More particularly, at least 90% of the total number of all fifth light sources are associated with the second filament surface. Even more particularly, all fifth light sources are associated with the second filament surface.

[0051] The terms "visible", "visible light", or "visible emission", and similar terms, refer to light having one or more wavelengths in the range of about 380-780 nm. UV may, in this specification, particularly refer to wavelengths selected from the range of 200-380 nm. The terms "light" and "radiation" are used interchangeably herein, unless it is clear from the context that the term "light" refers only to visible light. Thus, the terms "light" and "radiation" may refer to UV radiation, visible light, and IR radiation. In certain embodiments, particularly for lighting applications, the terms "light" and "radiation" refer to (at least) visible light. The term "purple light" or "purple emission" particularly relates to light having a wavelength in the range of about 380-440 nm. The term "blue light" or "blue emission" particularly relates to light having a wavelength in the range of about 440-490 nm (including some purple and cyan hues). The term "green light" or "green emission" particularly relates to light having a wavelength in the range of about 490-560 nm. The term "yellow light" or "yellow emission" particularly relates to light having a wavelength in the range of about 560-590 nm. The term "orange light" or "orange emission" particularly relates to light having a wavelength in the range of about 590-620. The term "red light" or "red emission" particularly relates to light having a wavelength in the range of about 620-750 nm. The term "cyan" may refer to one or more wavelengths selected from the range of about 490-520 nm. The term "amber" may refer to one or more wavelengths selected from the range of about 585-605 nm, for example, about 590-600 nm.

[0052] Thus, the third light source may in an embodiment provide blue light, particularly having a centroid wavelength in the range of 440-490 nm, and even more particularly having a centroid wavelength in the range of about 440-480 nm. In particular, the third light source is a solid-state light source.

[0053] Thus, in an embodiment, the fourth light source may provide green light, particularly having a centroid wavelength in the range of 520-560 nm. Alternatively or additionally, in an embodiment, the fourth light source may provide cyan light, particularly having a centroid wavelength in the range of 490-520 nm. Thus, in an embodiment, the fourth light source may comprise one or more types of fourth light sources configured to generate light having one or more centroid wavelengths in a wavelength range of about 490-560 nm. In particular, the fourth light source is a solid-state light source. In other embodiments, the fourth light source may be configured to generate cyan green light selected from a range of about 480-560 nm. For example, in an embodiment, the fourth light source may comprise one or more types of fourth light sources configured to generate light having one or more centroid wavelengths in a wavelength range of about 480-560 nm.

[0054] In an embodiment, the fifth light source may be configured to generate red light having one or more wavelengths selected from the wavelength range of 620-750 nm, even more specifically from the wavelength range of 620-650 nm, more specifically from the wavelength range of 620-640 nm. In a particular embodiment, the fifth light source may be configured to generate red light having a peak wavelength selected from the wavelength range of 620-650 nm, more specifically from the wavelength range of 620-640 nm. In a particular embodiment, the fifth light source may be configured to generate red light having a centroid wavelength selected from the wavelength range of 620-650 nm, more specifically from the wavelength range of 620-640 nm. In an embodiment, the fifth light source includes a fifth light source, the fifth light source configured to generate a fifth source light having a peak wavelength and / or centroid wavelength selected from the wavelength range of 620-650 nm, more specifically from the wavelength range of 620-640 nm. In particular, the fifth light source is a solid-state light source.

[0055] The term "centroid wavelength", also referred to as λc, is known in the art and refers to the wavelength value at which half the light energy is at shorter wavelengths and half the energy is at longer wavelengths, the value being written in units of nanometers (nm). The centroid wavelength is calculated according to the formula λc=Σλ * is the wavelength that divides the integral of the spectral power distribution, as represented by I(λ) / (ΣI(λ), into two equal parts, where the summation is over the wavelength range of interest and I(λ) is the spectral energy density (i.e., the integral of the wavelength-intensity product over the emission band, normalized to the integrated intensity). The centroid wavelength may be determined, for example, at operating conditions.

[0056] The third light, the fourth light, and the fifth light may have different centroid wavelengths. The mutual distance between the centroid wavelengths may be at least 20 nm, for example, particularly at least 30 nm, in an embodiment.

[0057] In embodiments, the LED filament may be based on blue- and green-emitting solid-state light sources as well as red-emitting solid-state light sources in addition to white-emitting light sources, which may in particular be based on blue-emitting solid-state light and corresponding luminescent materials (which provide warm white light and cool white light, respectively).

[0058] Instead of a green-emitting solid-state light source, a blue-emitting solid-state light source in combination with a green light luminescent material may also be applied.Similarly, instead of a red-emitting solid-state light source, a blue-emitting solid-state light source in combination with a red-emitting luminescent material may also be applied.

[0059] The term "luminescent material" refers in particular to a material capable of converting a first radiation, in particular one or more of UV radiation and blue radiation, into a second radiation. In general, the first radiation and the second radiation have different spectral power distributions. Therefore, instead of the term "luminescent material", the term "luminescent converter" or "converter" may also be applied. In general, the second radiation has a spectral power distribution at a wavelength greater than that of the first radiation, which is the case of so-called down-conversion. However, in certain embodiments, the second radiation has a spectral power distribution with an intensity at a wavelength less than that of the first radiation, which is the case of so-called up-conversion. In embodiments, the term "luminescent material" may refer in particular to a material capable of converting radiation, for example, into visible light and / or infrared light. For example, in embodiments, the luminescent material may be capable of converting one or more of UV radiation and blue radiation into visible light. The luminescent material may also convert radiation into infrared radiation (IR) in certain embodiments. Thus, when excited with radiation, the luminescent material emits radiation. Generally, the luminescent material is a down-converter, i.e., radiation of a smaller wavelength is converted to radiation having a larger wavelength (λ ex <λ em ), in certain embodiments, the luminescent material may include an up-converter luminescent material, i.e., radiation of a larger wavelength is converted to radiation having a smaller wavelength (λ ex >λ em ). In embodiments, the term "luminescence" may refer to phosphorescence. In embodiments, the term "luminescence" may also refer to fluorescence. Instead of the term "luminescence", the term "emission" may also be applied. Thus, the terms "first radiation" and "second radiation" may refer to excitation radiation and luminescence (radiation), respectively. Similarly, the term "luminescent material" may refer to phosphorescence and / or fluorescence in embodiments. The term "luminescent material" may also refer to multiple different luminescent materials.

[0060] In a particular embodiment, the luminescent material applied to provide a white emitting light source is ABO 12 :Ce type luminescent materials, where A comprises one or more of Y, La, Gd, Tb, and Lu, and B comprises one or more of Al, Ga, In, and Sc.

[0061] Thus, the light source may include a solid-state light source. Furthermore, one or more of the light sources may include a luminescent material. The luminescent material may be included with the solid-state light source, such as a PC LED, or may be configured downstream of the solid-state light source, such as a direct LED, with the luminescent material configured downstream of the LED, for example, within a light-transmissive material (in which the luminescent material may be embedded).

[0062] In an embodiment, the LED filament device, more particularly the sandwich LED filament, may comprise at least five of each of the first light source, the second light source, the third light source, the fourth light source, and the fifth light source. More particularly, in an embodiment, each of the first light source, the second light source, the third light source, the fourth light source, and the fifth light source comprises a solid-state light source. Furthermore, in an embodiment, the first light source and the second light source may be arranged in two parallel rows (461, 462). Still further, in an embodiment, the third light source, the fourth light source, and the fifth light source may be arranged in two or three parallel rows (463, 464, 465).

[0063] The first light source may have a first pitch p1. The second light source may have a second pitch p2. In particular, in an embodiment, 0.5≦p1 / p2≦2, more particularly 0.75≦p1 / p2≦1.25, even more particularly 0.9≦p1 / p2≦1.1, for example p1 / p2=1.

[0064] Further, the third light source may have a third pitch p3. The fourth light source may have a fourth pitch p4. The fifth light source may have a fifth pitch p5. In an embodiment, 0.5≦p4 / p3≦2, more particularly 0.75≦p4 / p3≦1.25, even more particularly 0.9≦p4 / p3≦1.1, for example p4 / p3=1. Further, in an embodiment, 0.5≦p5 / p3≦2, more particularly 0.75≦p5 / p3≦1.25, even more particularly 0.9≦p5 / p3≦1.1, for example p5 / p3=1. Still further, in an embodiment, 0.5≦p5 / p4≦2, more particularly 0.75≦p5 / p4≦1.25, even more particularly 0.9≦p5 / p4≦1.1, for example p5 / p4=1. The third light source, the fourth light source and the fifth light source may in an embodiment be distributed over two rows, in particular evenly distributed. In another embodiment, the third light source, the fourth light source and the fifth light source may in an embodiment be distributed over three rows. In the latter embodiment, each row may comprise a single type of third light source, fourth light source and fifth light source, or each row may comprise two or three types of third light source, fourth light source and fifth light source.

[0065] The pitch may be selected from the range of 0.02 to 10 mm, for example from the range of 0.02 to 5 mm, for example from the range of 0.05 to 2 mm. The shortest distance between the solid-state light sources in a row may in embodiments be ≦3 mm, more particularly ≦2 mm, most particularly ≦1 mm. Otherwise, spots may be observed. This is especially true when solid-state light sources emitting different colors are used. The length and width of the solid-state light sources may in particular be ≦1 mm, more particularly ≦0.8 mm, most particularly ≦0.7 mm. Smaller solid-state light sources may be used, especially if there is a large number of solid-state light sources, since not as much light may be needed. Smaller solid-state light sources (less epi) may be cheaper. The pitch between the solid-state light sources in a row may in embodiments be in particular ≦3 mm, more particularly ≦2 mm, most particularly ≦1 mm (see above). The shortest distance between the solid-state light sources in different rows may be small, since the architecture may mimic a single filament. This distance may in embodiments be ≦3 mm, more particularly ≦2 mm, and most particularly ≦1 mm. The minimum distance between the solid state light sources in a row may be about the same as the minimum distance between the solid state light sources in different rows.

[0066] In an embodiment, the number of the third light sources, the fourth light sources, and the fifth light sources may be approximately equal. Thus, in a particular embodiment, the number of the third light sources n3, the number of the fourth light sources n4, and the number of the fifth light sources n5 may differ from each other within a maximum of 15% of the average value for n3, n4, and n5 (i.e., the average value for n3+n4+n5).

[0067] As mentioned above, in embodiments, a sandwich configuration may be provided, which in embodiments may comprise a first LED filament and a second LED filament, optionally with an intermediate layer between them. In other embodiments, a single LED filament may be applied with all the solid state light sources generally on one side, and the solid state light sources may be folded to provide a folded filament, optionally with an intermediate layer between them.

[0068] In particular, in embodiments, the intermediate layer may comprise a thermally conductive element that may facilitate heat dissipation and / or heat diffusion. In this manner, the lifetime of the device may be longer and / or the spectral characteristics may be more stable over a wider power range.

[0069] Thus, in particular, the first LED filament surface, the second LED filament surface, and (iii) the intermediate layer may be comprised by a sandwich configuration, the intermediate layer being configured between at least a portion of the first LED filament surface and at least a portion of the second LED filament surface.

[0070] The third light source, the fourth light source, and the fifth light source may be used to generate white light by themselves, or to generate light for further adjusting the white light of the first light source and / or the second light source. It may be useful if two or more of the third light source, the fourth light source, and the fifth light source are at least partially surrounded by a light-transmitting material. This may protect the light source or the solid-state light source, but it may also, in embodiments, promote light mixing, especially if the light-transmitting material scatters at least some of the light. Thus, in embodiments, one or more of the third light source, the fourth light source, and the fifth light source, particularly two or more, and even more particularly all three, may be at least partially surrounded by a light-transmitting material. Thus, one or more of the third light source, the fourth light source, and the fifth light source may be at least partially embedded by a light-transmitting material. Thus, in an embodiment, one or more of the third light source, the fourth light source, and the fifth light source may be at least partially embedded by an encapsulant including a light-transmitting material. The encapsulant may encapsulate one or more different types of light sources. In an embodiment, there may be two or more different encapsulants, such as a first encapsulant contained by the first light source, a second encapsulant contained by the second light source, and one or more encapsulants encapsulating one or more of the third light source, the fourth light source, and the fifth light source.

[0071] The phrase "one or more encapsulants encapsulating one or more of the third light source, the fourth light source, and the fifth light source" can refer to different embodiments, including embodiments as a single encapsulant that encapsulates all three types, embodiments of a single encapsulant that encapsulates two different types, embodiments of a single encapsulant that encapsulates a single type, and embodiments of a first encapsulant that encapsulates two types of light sources and a second encapsulant that encapsulates another type of light source.

[0072] In an embodiment, the fourth light source and the fifth light source may be at least partially surrounded by a light-transmitting material. In yet another embodiment, the third light source, the fourth light source, and the fifth light source. Thus, in a particular embodiment, the LED filament device may further comprise a light-transmitting material, and the fourth light source and the fifth light source, and optionally the third light source, are configured to be at least partially embedded in the light-transmitting material. In particular, the light-transmitting material is transparent to the blue third light, the green fourth light, and the red fifth light. Furthermore, in a particular embodiment, the light-transmitting material is translucent. For example, at least 20%, for example at least 30%, of the light of one or more of the third light source, the fourth light source, and the fifth light source that enters the light-transmitting material will exit the light-transmitting material only via at least one scattering (downstream). In a particular embodiment, the light-transmitting material comprises a silicone material containing scattering particles. The representative particle size is known from the prior art and may, for example, be selected in an embodiment from the range of 0.5 to 50 μm, although other dimensions may also be possible.

[0073] As mentioned above, the intermediate layer may have thermally conductive properties. The thermally conductive element may in particular comprise a thermally conductive material. The thermally conductive material may in particular have a thermal conductivity of at least about 20 W / (m * K), at least about 30 W / (m * For example, at least about 100 W / (m * K), in particular at least about 200 W / (m * In yet further particular embodiments, the thermally conductive material may have a thermal conductivity of at least about 10 W / (m *In some embodiments, the thermally conductive material may have a thermal conductivity of 0.1 K. In some embodiments, the thermally conductive material may include one or more of copper, aluminum, silver, gold, silicon carbide, aluminum nitride, boron nitride, aluminum silicon carbide, beryllium oxide, silicon carbide composites, aluminum silicon carbide, copper tungsten alloy, copper molybdenum carbide, carbon, diamond, and graphite. Alternatively or additionally, the thermally conductive material may include or consist of aluminum oxide. In this regard, in some embodiments, the intermediate layer comprises a metal layer. In some embodiments, the intermediate layer comprises one or more of (i) a copper layer, and (ii) an aluminum layer. In still other embodiments, the thermally conductive layer may comprise a carbon layer, such as carbon nanotubes, graphene, and the like. In some embodiments, the intermediate layer may comprise a carbon layer. The carbon-containing layer may also be thermally conductive. For example, the thermally conductive material may be applied based on a material with embedded particles, such as ceramic particles, or carbon nanoparticles, such as carbon nanotubes. Since the thermally conductive material may in embodiments be electrically conductive, such as a metal layer, in embodiments the thermally conductive element, particularly the metal layer, and the light source may not be configured in electrically conductive contact and therefore may not be part of an electrical circuit.

[0074] Since the third, fourth and fifth light sources can be used to further control the color point, it may be useful for some of the light of these light sources to be able to exit directly from the other side. Similarly, it may be useful for some of the white light from the first and / or second light sources to be able to exit directly from the other side. In other words, even if configured on one of the two filament sides, some of the light of the corresponding one of the light sources associated with a particular filament side can exit through the other of the two filament sides. For this purpose, it may be desirable for the support to be light-transmitting and for the (optional) intermediate layer to be light-transmitting.

[0075] However, it may be useful if the blue light of the third light source cannot escape through the other side, or can escape to a lesser extent. This may reduce the excitation of the luminescent material of the first light source and / or the second light source, which may undesirably change the color point and / or other optical properties of the LED filament light. This may also be true to a lesser extent, or may not be true at all, for the light of the fourth light source. Thus, in an embodiment, the intermediate layer may be one or more of (i) reflective and (ii) light absorbing for one or more of (a) the blue third light and (b) the green fourth light. In particular, the intermediate layer may be one or more of (i) reflective and (ii) light absorbing for at least the blue third light and optionally the green fourth light. Even more particularly, in an embodiment, the thermally conductive element may be one or more of (i) reflective and (ii) light absorbing for one or more of (a) the blue third light and (b) the green fourth light. Thus, in particular, the thermally conductive element may be one or more of: (i) reflective and (ii) light absorbing, at least with respect to the blue third light and optionally with respect to the green fourth light.

[0076] Additionally, as discussed above, in certain embodiments, the intermediate layer may be selected to allow at least a portion of the light generated on one side to escape the LED filament on the other side (LED filament sandwich configuration). Thus, for example, in embodiments, the intermediate layer may include a light-transmitting portion, such as defined by an opening or a light-transmitting material.

[0077] In particular, the intermediate layer and the third light source (on the one hand) may be configured such that the third light may propagate to the other side relatively less than may be the case for the fifth light and optionally the fourth light. Thus, in an embodiment, an extension of the optical axis of the third light source may occlude the thermally conductive element. As will become clearer below, the intermediate layer, and in a more particular embodiment the thermally conductive element, may be configured such that there are one or more openings in the thermally conductive element (or between the thermally conductive element portions). Thus, in particular, in an embodiment, an extension of the optical axis of the third light source may not occlude such openings in the thermally conductive element (or between the thermally conductive element portions).

[0078] Furthermore, as mentioned above, the intermediate layer (on the other hand) and the first light source and / or the second light source may be configured such that a portion of the first light and / or the second light generated on one side can escape the LED filament (LED filament sandwich configuration) on the other side. Thus, in an embodiment, an LED filament device comprising an intermediate layer may be configured such that a portion of one or more of the first white light and the second white light can escape the sandwich configuration via the second LED filament side. As will become clearer below, this can be realized in an embodiment in which the intermediate layer, and in a more specific embodiment the thermally conductive element, may be configured such that there are one or more openings in the thermally conductive element (or between the thermally conductive element parts). Instead of openings, a light-transmitting material (e.g. a light-transmitting polymer material) may also be used. This light-transmitting material may be transparent or semi-transparent. Thus, in a particular embodiment, the intermediate layer may not be completely transparent or opaque (reflective), but may be partially transparent in some places and partially reflective in some places.

[0079] As mentioned above, in certain embodiments, the sandwich configuration may be provided by a single LED filament. Thus, in certain embodiments, the LED filament device may comprise an LED filament, which is configured to be folded in half to define a first LED filament surface and a second LED filament surface configured opposite each other. In such embodiments, the intermediate layer may be configured between at least a portion of the first LED filament surface and at least a portion of the second LED filament surface. In particular, in such embodiments, the LED filament comprises a support having a solid-state light source attached to one side. The support has a first side to which the solid-state light source is attached and a second side to which the solid-state light source may not be attached. The support may be configured to be folded in half, thereby providing a folded LED filament having a first LED filament surface with a subset of the solid-state light sources and a second filament surface with another subset of the light sources. However, in practice, the first LED filament surface and the second filament surface are the same side of a shared support.

[0080] To allow light to propagate from one LED filament surface to another, the support may transmit at least a portion of the light. Thus, the support may comprise a light-transmitting material (such as, for example, a flex foil). Thus, in a particular embodiment, the LED filament comprises a support, at least a portion of which is light-transmitting to one or more of the first white light and the second white light. In particular, an intermediate layer may be configured between a portion of the first LED filament surface and a portion of the second LED filament surface. Advantageously, the LED filament may be at least partially folded around an intermediate layer, such as a thermally conductive layer. The folding is in particular along the length axis of the LED filament.

[0081] In other embodiments, two LED filaments may be applied to provide a sandwich configuration. In particular, in such an embodiment, the LED filament comprises a corresponding support, and a corresponding solid-state light source is attached, in particular on one side of each of the corresponding supports. The support has a first side on which the solid-state light source is attached and a second side on which the solid-state light source may not be attached. The two supports may be configured with each other by configuring an intermediate layer between them to operatively connect the sides without the solid-state light source to each other. This provides a (sandwich) LED filament having a first LED filament surface provided by one LED filament and a second LED filament surface provided by the other LED filament. Thus, in a particular embodiment, the LED filament device comprises a first LED filament (1100') defining a first LED filament surface and a second LED filament (1100'') defining a second LED filament surface, the first filament and the second filament (1100'') being included by a sandwich configuration. In particular, an intermediate layer, more particularly a thermally conductive layer, may be configured between at least a portion of the first LED filament surface and at least a portion of the second LED filament surface.

[0082] To allow light to propagate from one LED filament surface to another, the supports of both LED filaments may transmit at least a portion of the light. Thus, the supports may comprise a light-transmitting material. Thus, in an embodiment, the first LED filament (1100') and the second LED filament (1100'') comprise supports, at least a portion of each of which is light-transmitting to one or more of the first white light and the second white light. In particular, as described above, an intermediate layer is configured between a portion of the first LED filament (1100') and a portion of the second LED filament (1100''). For example, the supports may comprise a light-transmitting polymer material.

[0083] Thus, the one or more supports and intermediate layers may be configured to allow some light of one or more of the light sources to exit the (sandwich) LED filament from a side of the LED filament other than the side on which the light source is configured.

[0084] The amount of light that can escape from the opposite LED filament face can be in the range of about 0.5-25%, such as 1-15%, of the light of the first light source and / or the second light source. Furthermore, in certain embodiments, the amount of light that can escape from the opposite LED filament face can be in the range of about 0.5-35%, such as 1-30%, of the light of the fifth light source and / or the optional fourth light source, where the percentages are based on power in watts in the visible wavelength range.

[0085] The intermediate layer, more particularly the thermally conductive element, may comprise one or more openings and / or may consist of several parts. For example, in an embodiment, the thermally conductive element may comprise an elongated layer, in particular in the middle of the layer, with openings arranged in an array. Alternatively or additionally, the thermally conductive element may comprise several parts, which may be arranged in parallel with openings between them. By configuring the intermediate layer, in particular the thermally conductive element and the third light source, and optionally the fourth light source, crosstalk of the (blue) third light into the luminescent material of the first light source or the second light source may be limited.

[0086] Thus, in an embodiment, the intermediate layer may be an elongated layer comprising a first thermally conductive element portion and a second thermally conductive element portion, with one or more openings between the first and second thermally conductive element portions. The first and second thermally conductive element portions may be physically coupled to each other or may be separate elements. Thus, in a particular embodiment, the first and second thermally conductive element portions with one or more openings between them may be a monolithic thermally conductive element.

[0087] Furthermore, the LED filament device may be operatively coupled to or may comprise a control system, which may be external to the LED filament, for example external to the sandwich filament, but operatively coupled to the LED filament.

[0088] In particular, the control system may control one or more of the first light source and the second light source. The control system may also control one or more of the third light source, the fourth light source, and the fifth light source. Even more particularly, the control system may control one or more of the first light source, the second light source, the third light source, the fourth light source, and the fifth light source. Thus, in particular, the LED filament device may further comprise a control system. Furthermore, the LED filament device may be configured in an embodiment to generate a device light including one or more of a first white light, a second white light, a blue third light, a green fourth light, and a red fifth light. In particular, in an embodiment, the control system may be configured to control the spectral power distribution of the device light. Thus, in an embodiment, the control system is configured to individually control the first light source, the second light source, the third light source, the fourth light source, and the fifth light source.

[0089] As mentioned above, one or more of the first light source and the second light source may provide white light with different CCT. When changing the ratio of the first light and the second light, the color point may be relatively far from the BBL, so that a white light that may be (slightly) off-white may be generated. This can be adapted, for example, by adding green light. Thus, in an embodiment, the control system may be configured to generate a (white) device light including (a) one or more of the first white light and the second white light, and (b) one or more of the blue third light, the green fourth light, and the red fifth light, while maintaining a distance to the blackbody locus of up to 10 SDCM, for example up to 5 SDCM, in the operating mode. Furthermore, the CCT may be increased by adding blue light, or decreased by adding red light. In certain embodiments, the control system may be configured to generate, in an operational mode, (a) a first white device light (1001') including a first white light and a second white light, and (b) a second white device light (1001'') including a blue third light, a green fourth light, and a red fifth light. The second white device light (1001'') has a color point above the blackbody locus.

[0090] In an embodiment, in an operational mode, the first light source in the first set and the third and fourth light sources in the first set may be configured together to provide white device light having a correlated color temperature selected from the range of 2700-4000 K. Thus, with the present invention, a wide CCT range may be possible, from a relatively low one selected from the range of 1800-2400 K to a relatively high one such as selected from the range of 5500-6500 K.

[0091] The lowest correlated color temperature of the device light may be based in particular on the light of the first light source. However, the correlated color temperature may be further reduced, for example by mixing in part of the light of the (optional) fifth light source (see also below). The highest correlated color temperature of the device light may be based in particular on the light of the second light source. However, the correlated color temperature may be further increased, for example by mixing in part of the light of the third light source.

[0092] Moreover, with the present invention, the correlated color may be controlled while remaining relatively close to the black body locus (BBL), and therefore white light may be provided over a relatively wide range of correlated color temperatures while remaining within 10 SDCM of the BBL, or even less (see also above).

[0093] As mentioned above, a fifth light source may also be available. Such a fifth light source may be configured to generate red light. Using the fifth light source, the optical properties of the device light may be further controlled. The CCT range may be increased, the color gamut may be increased, and the CRI may also be improved.

[0094] In certain embodiments, in an operational mode, the first light source, the third light source, the fourth light source, and the fifth light source in the first set may be configured to collectively provide white (device) light having a correlated color temperature selected from the range of 2700 to 4000 K, or even greater, such as up to 4500 K, or even greater.

[0095] In certain embodiments, in an operational mode, the third light source, the fourth light source, and the fifth light source in the first set may be configured together to provide white (device) light having a correlated color temperature selected from the range of 1900 to 6500 K, in particular with a CCT tunable range of at least 1000 K, such as at least 2000 K.

[0096] Here, the term CCT tunable range refers to a range defined between the lowest and highest correlated color temperatures over which the color temperature can be controlled.

[0097] In certain embodiments, in an operational mode, the second light source (in the first set), optionally in combination with one or more of (i) the third light source (in the first set), the fourth light source (in the first set), and the optional fifth light source (in the first set), may be configured to provide white (device) light having a correlated color temperature selected from the range of 2300 to 6500 K, in particular with a CCT tunable range of at least 1000 K, such as at least 2000 K.

[0098] As mentioned above, in an embodiment, the LED filament device may further comprise a luminescent material, and the first light source is in particular based on (a) a first light source configured to generate a first light source light, and (b) a luminescent material configured downstream of the first light source and configured to convert at least a portion of the first light source light into luminescent material light. In particular, in an embodiment, the first light comprises the first light source light and the luminescent material light. Furthermore, as mentioned above, in an embodiment, the first light source comprises a solid-state light source. In this way, the first light source may be based on a luminescent material.

[0099] However, other embodiments may also be provided, for example for generating a second light, or for generating a third light or a fourth light or a fifth light.

[0100] Referring to the second light, in an embodiment, the LED filament device may further comprise a luminescent material, and the second light source is particularly based on (a) a second light source configured to generate a second light source light, and (b) a luminescent material configured downstream of the second light source and configured to convert at least a portion of the second light source light into luminescent material light. In particular, in an embodiment, the second light includes the second light source light and the luminescent material light. Furthermore, as described above, in an embodiment, the second light source includes a solid-state light source. In this way, the second light source may be based on a luminescent material.

[0101] It should be noted that the luminescent materials for these luminescent material-based embodiments of the second light source may be different from the luminescent materials for the luminescent material-based embodiments of the first light source. However, in embodiments, the second light source for these luminescent material-based embodiments of the second light source may be different from the first light source for the luminescent material-based embodiments of the first light source, although in other embodiments they may also be of the same type. For example, the light source for the first light source and the light source for the second light source may be controlled separately, especially when the same type of blue LED is used, such as from the same bin.

[0102] Therefore, in a more general embodiment, the light source may be based on a luminescent material, and in an embodiment, the LED filament device may further comprise a luminescent material, and the light source is in particular based on (a) a light source, in particular a solid-state light source, configured to generate a light source light, and (b) a luminescent material configured downstream of the light source and configured to convert at least a portion of the light source light into luminescent material light. In particular, in an embodiment, the light of the light source may include luminescent material light, and in certain embodiments may also include light source light (if there is no complete conversion). In this way, the light source may be based on a luminescent material.

[0103] The encapsulant contained by the first light source may contain a different luminescent material than the encapsulant contained by the second light source. In an embodiment, both encapsulants may contain the same light-transmitting material, but with different luminescent materials embedded in the encapsulants. Thus, the first light source and the second light source may contain different encapsulants, which in an embodiment may differ in particular in their luminescent materials.

[0104] It should be noted that in an embodiment, the third light source may include a third light source, and the fourth light source may include a fourth light source. In particular, these may be solid-state light sources of different bins, and in an embodiment, may be direct LEDs. Furthermore, as described above, in an embodiment, the fifth light source may include a solid-state light source. It should be noted that the fifth light source may be a fifth light source, such as a red-emitting LED, and therefore the fifth light and the fifth light source light may be essentially the same.

[0105] In an embodiment, the first light source comprises a first light source, in particular a first solid-state light source, which provides a first light in combination with a luminescent material. Furthermore, in an embodiment, the second light source comprises a second light source, in particular a second solid-state light source, which provides a second light in combination with a (different) luminescent material. The first light source and the second light source may be of the same bin. The first light source and the third light source may be of the same bin. The second light source and the third light source may be of the same bin. The first light source, the second light source, and the third light source may be of the same bin. The former two may be applied in combination with a luminescent material in an embodiment, and the latter may be used as a source of blue light (third light) in an embodiment.

[0106] Thus, the LED filament device may comprise a first light source, a second light source, a third light source, a fourth light source, and optionally a fifth light source. As mentioned above, in certain embodiments, the first light source and the second light source may be of the same bin. In particular, the first light sources (of at least a first set) may be controlled as a (first) subset of the first light sources. In particular, the second light sources (of at least a second set) may be controlled as a (second) subset of the second light sources.

[0107] In particular, the third light sources (of at least the third set) may be controlled as a (third) subset of the third light sources. In particular, the fourth light sources (of at least the fourth set) may be controlled as a (fourth) subset of the fourth light sources. In particular, the (optional) fifth light source (of at least the (optional) fifth set) may be controlled as a (fifth) subset of the (optional) fifth light sources. In particular, all light sources may be solid-state light sources. In a particular embodiment, the control system may control the first, second, third and fourth subsets, and the optional fifth subset, individually.

[0108] The third light source may be configured to generate a third source light. The third light may essentially be a third source light. For example, the third light source may be a direct LED. The fourth light source may be configured to generate a fourth source light. The fourth light may essentially be a fourth source light. For example, the fourth light source may be a direct LED. The fifth light source may be configured to generate a fifth source light. The fifth light may essentially be a fifth source light. For example, the fifth light source may be a direct LED.

[0109] Above, some embodiments have been described in relation to five light sources. However, in embodiments, the invention may include embodiments having only the first light source or only the second light source. The invention may also include embodiments having five or six light sources, where the fifth light source is configured to generate amber light but not red light, or the fifth light source is configured to generate red light and the sixth light source is configured to generate amber light. In particular, any light source that provides colored light may be operatively coupled to the second surface.

[0110] For example, in an embodiment, four types of light sources may be applied, including a light source configured to generate white light (particularly the first or second light source), a light source configured to generate blue light (third light source), a light source configured to generate green light (fourth light source), and a light source configured to generate red light (fifth light source).

[0111] For example, in another embodiment, five types of light sources may be applied, including a light source (particularly a first light source) configured to generate warm white light, a light source (particularly a second light source) configured to generate cold white light, a light source (third light source) configured to generate blue light, a light source (sixth light source) configured to generate lime light, and a light source (fifth light source) configured to generate red light. The lime light may have one or more wavelengths in a wavelength range of 560 to 570 nm. In particular, the lime light may have a centroid wavelength of, for example, about 565 nm in the wavelength range of 560 to 570 nm.

[0112] For example, in yet another embodiment, four types of light sources may be applied, including a light source configured to generate white light (particularly the first or second light source, or both types), a light source configured to generate blue light (third light source), a light source configured to generate green light having a centroid wavelength in the range of 520 to 560 nm (fourth light source), a light source configured to generate cyan light having a centroid wavelength in the range of 480 to 520 nm, for example 490 to 520 nm (again fourth light source), and a light source configured to generate red light (fifth light source).

[0113] However, other embodiments may also be possible.

[0114] In one aspect, the present invention also provides an LED filament device comprising: (i) a first LED filament surface; (ii) a second LED filament surface; (iii) an intermediate layer; and (iv) a plurality of light sources. In particular, in an embodiment, a first set of light sources is associated with the first filament surface. In a particular embodiment, at least a first subset of these light sources of the first set is configured to generate light. In particular, the light of this first subset of light sources may be white light. In a particular embodiment, a second set of light sources is associated with the second filament surface. In particular, in an embodiment, at least a second subset of these light sources of the second set is configured to generate light. In an embodiment, the light of this second subset of light sources may be colored light (second colored light). Furthermore, in a particular embodiment, at least a third subset of these light sources of the second set is configured to generate light. In an embodiment, the light of this third subset of light sources may be a colored light (third colored light) having a different spectral power distribution than the light of this second subset of light sources. Still further, in an embodiment, the first LED filament surface, the second LED filament surface, and (iii) the intermediate layer may be included by a sandwich configuration. In particular, the intermediate layer is configured between at least a portion of the first LED filament surface and at least a portion of the second LED filament surface. Furthermore, in a particular embodiment, the intermediate layer may comprise a first thermally conductive element portion and a second thermally conductive element portion, and may have one or more openings between the first thermally conductive element portion and the second thermally conductive element portion. In an embodiment (see also above), the first thermally conductive element portion and the second thermally conductive element portion may form a monolithic thermally conductive element.Thus, in a particular embodiment, the present invention also relates to an LED filament device comprising: (i) a first LED filament surface; (ii) a second LED filament surface; (iii) an intermediate layer; and (iv) a plurality of light sources, wherein: (a) a first set of light sources is associated with the first filament surface, and at least a first subset of the light sources of the first set are configured to generate light, the light of the first subset of light sources being white light; (b) a second set of light sources is associated with the second filament surface, and at least a second subset of the light sources of the second set are configured to generate light, the light of the second subset of light sources being colored light (second colored light); and (c) a second set of light sources is associated with the second filament surface, and at least a second subset of the light sources of the second set are configured to generate light, the light of the second subset of light sources being colored light (second colored light); at least a third subset of the light sources of the first LED filament are configured to generate light, the light of the third subset of light sources being a colored light (third colored light) having a different spectral power distribution than the light of the second subset of light sources; (d) the first LED filament surface, the second LED filament surface, and (iii) the intermediate layer are comprised by a sandwich configuration, the intermediate layer being configured between at least a portion of the first LED filament surface and at least a portion of the second LED filament surface; and (e) the intermediate layer comprises a first thermally conductive element portion and a second thermally conductive element portion, and has one or more openings between the first thermally conductive element portion and the second thermally conductive element portion.

[0115] As will become apparent from the above, the sandwiched LED filament may in embodiments comprise a single (folded) support, and in other embodiments may comprise two supports. The folded support may in embodiments comprise one or two bends. As mentioned above, the support may in embodiments be flexible.

[0116] In particular, the LED filament device is configured to generate LED filament device light. Moreover, in embodiments, the spectral characteristics of the filament device light may be controllable. For example, one or more of the CRI, CCT, and color point may be controlled.

[0117] Therefore, in an embodiment, the LED filament device may further comprise or be operatively coupled to a control system, in particular the control system may be configured to control one or more of the spectral power distribution, color rendering index, correlated color temperature, and color point of the filament device light by individually controlling one or more of the first light source, the second light source, the third light source, the fourth light source, and optionally the fifth light source.

[0118] The term "controlling" and similar terms in particular refer to at least determining the behavior of an element or managing the operation of an element. Thus, in this specification, "controlling" and similar terms may refer to, for example, imposing a behavior on an element, such as, for example, measuring, indicating, activating, opening, transitioning, changing temperature, etc. (determining the behavior of an element or managing the operation of an element). Alternatively, the term "controlling" and similar terms may further include monitoring. Thus, the term "controlling" and similar terms may include imposing a behavior on an element, as well as imposing a behavior on an element and monitoring the element. Controlling an element can be performed by a control system, which may also be denoted as a "controller". Thus, the control system and the element may be functionally coupled, at least temporarily or permanently. The element may include the control system. In an embodiment, the control system and the element may not be physically coupled. Control can be performed via wired control and / or wireless control. The term "control system" may also refer to multiple different control systems that are specifically functionally coupled, of which, for example, one control system may be a master control system and one or more other control systems may be slave control systems. A control system may include a user interface or be functionally coupled to a user interface.

[0119] The control system may also be configured to receive and execute instructions from a remote controller. In an embodiment, the control system may be controlled via an app on a device, such as a portable device, such as a smartphone or an I-phone, a tablet, etc. The device may therefore not necessarily be coupled to the lighting system, but may be (temporarily) functionally coupled to the lighting system. In an embodiment, the control system may therefore (also) be configured to be controlled by an app on a remote device. In such an embodiment, the control system of the lighting system may be a slave control system or may control in a slave mode. For example, the lighting system may be identifiable by a code, in particular a unique code related to the corresponding lighting system. The control system of the lighting system may be configured to be controlled by an external control system, which has access to the lighting system based on knowledge of the (unique) code (entered by a user interface of an optical sensor, e.g. a QR code reader). The lighting system may also comprise means for communicating with other systems or devices, such as based on Bluetooth, WIFI, LiFi, ZigBee, BLE or WiMax, or another wireless technology.

[0120] A system, or an apparatus, or a device may perform an action in a "mode" or "operation mode" or "mode of operation". Similarly, in a method, an action, or a stage, or a step may be performed in a "mode" or "operation mode" or "mode of operation" or "operational mode". The term "mode" may also be indicated as a "control mode". This does not exclude that the system, or an apparatus, or a device may also be adapted to provide another control mode or multiple other control modes. Similarly, this may not exclude that one or more other modes may be performed before performing a mode and / or after performing a mode.

[0121] However, in an embodiment, a control system may be available that is adapted to provide at least the control mode. If other modes are available, the selection of such modes may in particular be performed via a user interface, although other options may also be possible, such as performing the mode depending on a sensor signal or a (time) scheme. An operating mode may also refer in an embodiment to a system, or an apparatus, or a device that can only operate in a single operating mode (i.e., "on", without further adjustability). Thus, in an embodiment, the control system may control depending on one or more of a user interface input signal, a (sensor) sensor signal, and a timer. The term "timer" may refer to a clock and / or a predefined time scheme. The control system may be used to control the filament light in an operating mode of different colors or different correlated color temperatures. Different colors or different color temperatures means in particular different color points.

[0122] In an embodiment, in a first operating mode, the LED filament device may be configured to generate a filament light having a CCT of up to 2400K, for example up to 2300K, for example up to 2000K, for example selected from the range of 1800-2300K, for example selected from the range of 1800-2100K, and in a further particular embodiment, a color point within 10 SDCM of the BBL. In an embodiment, in a second operating mode, the LED filament device may be configured to generate a filament light having a CCT of at least 2700K, for example at least 3000K, for example in an embodiment at least 3500K, for example selected from the range of 2700-6500K, for example selected from the range of 3000-6500K, and in a further particular embodiment, a color point within 10 SDCM of the BBL. In particular, the CRI may be at least 80, for example at least 85.

[0123] In an embodiment, in the operating mode, (cold) white light may be provided only by the second light source. In another embodiment, in the operating mode, (cold) white light may be provided by the second light source and optionally one or more of the third and fourth light sources. In this way, the CCT may be controllable while remaining relatively close to the BBL. Furthermore, in this way, the CCT may be at least 2700K or (much) higher, see also above. In an embodiment, in the operating mode, (warm) white light may be provided only by the first light source. In another embodiment, in the operating mode, (warm, or even warmer) white light may be provided by the first and fifth light sources. Furthermore, in this way, the CCT may be low, such as up to 2400K, or even (substantially) lower, such as less than 2200K, e.g. less than 2100K.

[0124] Some further embodiments are described below.

[0125] Furthermore, in certain embodiments, the LED filament may have a spiral or helical shape, which may be particularly useful for applications in retrofit lamps, such lamps may include one or more LED filaments.

[0126] As mentioned above, the LED filament may include a (light-transmitting) encapsulant that may at least partially surround the solid-state light source, in particular at least surround the light-emitting surface of the solid-state light source, such as a die. The encapsulant may include a light-transmitting material. In particular, in an embodiment, the light-transmitting material may include a polymeric material, such as a resin. However, alternative embodiments may also be possible. In certain embodiments, the light-transmitting material may include a luminescent material (see also above). Alternatively or additionally, in certain embodiments, the light-transmitting material may include a light-scattering material. In further particular embodiments, the light-transmitting material may include a light-transmitting host material, such as a polymeric material, such as a resin, and a luminescent material. The luminescent material may be embedded within the light-transmitting host material. In further particular embodiments, the light-transmitting material may include a light-transmitting host material, such as a polymeric material, such as a resin, and a scattering material. The scattering material may be embedded within the light-transmitting material. The scattering material may include light-reflecting particles. Instead of the term "light-transmitting material", the term "optically transmissive material" may also be applied.

[0127] In embodiments, all of the light solid-state light sources may be at least partially embedded within the light-transmissive material. In other embodiments, a subset of the solid-state light sources may be at least partially embedded within the light-transmissive material. In particular, the term "partially embedded" may indicate that light exiting the solid-state light sources can exit substantially only through the light-transmissive material.

[0128] In embodiments where the light-transmitting material includes a scattering material and no luminescent material, all solid-state light sources may be partially embedded within the light-transmitting material. In embodiments where the light-transmitting material includes a luminescent material, the solid-state light sources whose light is at least partially converted by the luminescent material may be partially embedded. However, other solid-state light sources may also be partially embedded within the light-transmitting material, provided that the light-transmitting material is substantially transparent to the light of such other light-generating devices.

[0129] In an embodiment, one or more, in particular all, of the first (solid state) light sources may be embedded in a light-transmitting material. Alternatively or additionally, one or more, in particular all, of the second (solid state) light sources may be embedded in a light-transmitting material. Alternatively or additionally, one or more, in particular all, of the fifth (solid state) light sources may be embedded in a light-transmitting material.

[0130] Such LED filaments are known and described, for example, in U.S. Pat. No. 8,400,051(B2), WO 2020016058, WO 2019197394, and the like, which are incorporated herein by reference. For example, U.S. Pat. No. 8,400,051(B2), which is incorporated herein by reference, describes a package having an elongated rod shape having a left end and a right end, in which a plurality of leads are integrally formed with a first resin such that a portion of the leads are exposed; a light emitting element fixed to at least one of the leads and electrically connected to at least one of the leads; and a second resin encapsulating the light emitting element, in which the leads are formed of metal, the entire bottom surface of the light emitting element is covered with at least one of the leads, the entire bottom surface of the package is covered with a first resin, and the first resin is integrally formed with a portion covering the bottom surface of the package and is formed such that an upper surface of the lead is exposed. the first and second resins being formed of optically transparent resins, the second resin being filled into the upper portion of the sidewalls of the first resin and containing a fluorescent material having a higher specific gravity than the second resin, lead wires being used for external connection and having outer lead portions protruding from the left and right ends in the longitudinal direction of the package, the fluorescent material being arranged to be concentrated near the light-emitting element and being excited by a portion of the light emitted by the light-emitting element, thereby emitting a color different from the color of the light emitted by the light-emitting element, and the sidewalls transmitting a portion of the light emitted by the light-emitting element and entering the sidewalls and a portion of the light emitted from the fluorescent material to a portion covering the bottom of the package.

[0131] In an embodiment, one or more filaments, particularly all filaments, may have a substantially straight shape. In yet another embodiment, one or more filaments, particularly all filaments, may have a curved shape. In yet another embodiment, one or more filaments, particularly all filaments, may have a spiral shape. In yet another embodiment, one or more filaments, particularly all filaments, may have a helical shape. If two or more filaments have a spiral or helical shape, in an embodiment, two of them may have similarly configured windings. Other shapes of filaments may also be possible, such as having characteristic shapes, such as letters, numbers, flowers, leaves, or other shapes. In particular, in an embodiment, the filaments have a spiral or helical shape.

[0132] The light-generating device may generally comprise a light-transmitting envelope ("bulb"), e.g. a light-transparent envelope, e.g. a glass envelope in an embodiment. The envelope may at least partially, and even more particularly substantially, surround one or more filaments. The light-transmitting envelope may have an envelope height (e.g. as defined by standard shapes B35, A60, ST63, G90, etc.). The first support structure may have a length of at least 20%, e.g. in an embodiment up to about 80%, of the height of the light-transmitting envelope. In particular, the envelope is transparent to (visible) light.

[0133] Furthermore, the light-generating device may be equipped with a screw base, such as type E27, but other connectors, for example for connecting to a socket, may also be possible.

[0134] In yet a further aspect, the present invention also provides an LED filament device as defined herein, the LED filament device being a retrofit lamp. In yet a further aspect, the present invention also provides a lamp or luminaire comprising an LED filament device as defined herein. The luminaire may further comprise a housing, optical elements, louvers, etc. The lamp or luminaire may further comprise a housing enclosing the light-generating device. The lamp or luminaire may comprise an optical window in the housing, or a housing opening, through which the system light may exit the housing.

[0135] In particular, in an embodiment, the present invention provides an LED filament device as defined herein, which is a retrofit lamp, and wherein the LED filament has a spiral or helical shape. [Brief description of the drawings]

[0136] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which: [Figure 1a] 1 illustrates several embodiments and aspects. [Figure 1b] 1 illustrates several embodiments and aspects. [Figure 1c] 1 illustrates several embodiments and aspects. [Figure 1d] 1 illustrates several embodiments and aspects. [Figure 1e] 1 illustrates several embodiments and aspects. [Figure 1f] 1 illustrates several embodiments and aspects. [Diagram 2] 1 illustrates a schematic diagram of an embodiment of an application example. [Diagram 3] Further embodiments and applications are illustrated diagrammatically. [Figure 4] Further embodiments and applications are illustrated diagrammatically.

[0137] The schematic drawings are not necessarily to scale. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0138] Fig. 1a shows a schematic representation of an embodiment of a single-sided LED filament 1100 having a light source 100 essentially in a single plane. The light source 100 may comprise a first light source 110, a second light source 120, a third light source 130, a fourth light source 140 and a fifth light source 150. In the top of Fig. 1a a cross-section in the plane of the LED filament 1100 is shown diagrammatically. On the right side of Fig. 1a a cross-section parallel to the plane of the LED filament 1100 is shown diagrammatically.

[0139] In an embodiment, the first light source 110 may be configured to generate a first white light 111 having a first correlated color temperature CCT1. In particular, the first light source 110 is associated with the first filament surface 1110. In an embodiment, the second light source 120 may be configured to generate a second white light 121 having a second correlated color temperature CCT2. In particular, the second light source 120 is associated with the first filament surface 1110. In particular, in an embodiment, CCT2-CCT1≧500K. In an embodiment, the third light source 130 may be configured to generate a blue third light 131. In an embodiment, the third light source 130 is associated with the second filament surface 1120. In an embodiment, the fourth light source 140 may be configured to generate a green fourth light 141. In an embodiment, the fourth light source 140 is associated with the second filament surface 1120. In an embodiment, the fifth light source 150 may be configured to generate a red fifth light 151. In an embodiment, the fifth light source 150 is associated with the second filament surface 1120.

[0140] Reference numbers 461 and 462 indicate rows in which corresponding first light sources 110 and second light sources 120 may be arranged. It should be noted that the first light sources 110 and second light sources may be distributed over both rows 461, 462.

[0141] References P1, P2, P3, P4, P5 indicate corresponding pitches of the first light source 110, the second light source 120, the third light source 130, the fourth light source 140, and the fifth light source 150. References 111, 121, 131, 141, 151 refer to corresponding lights of the first light source 110, the second light source 120, the third light source 130, the fourth light source 140, and the fifth light source 150. Reference 1101 indicates an LED filament light.

[0142] Embodiment I(W) shows a schematic diagram of a first light source 110 and a second light source 120, each based on a solid-state light source 10, which may be the same bin, but may be different bins, configured to generate a light source light, which is at least partially converted into a luminescent material light by a corresponding first luminescent material 210 and a second luminescent material 220 (with different spectral power distributions for the first luminescent material light and the second luminescent material light). Thus, the solid-state light source 10 is encapsulated with at least a light-transmitting material, which in an embodiment may be the same for both light sources, but in which the luminescent materials 210, 220 may be embedded, respectively.

[0143] The first light 111 may include a first luminescent material light of the first luminescent material 210 and optionally a source light of a (corresponding) solid-state light source light. The second light 121 may include a second luminescent material light of the second luminescent material 220 and optionally a source light of a (corresponding) solid-state light source light. Reference numeral 445 denotes a light-transmissive material, such as silicone, in which the respective luminescent materials may be embedded.

[0144] Reference numeral 1110 denotes a first filament surface of the LED filament 1100 .

[0145] Embodiment II(C1) shows a schematic representation of an embodiment in which the third light source 130, the fourth light source 140 and the fifth light source 150 are distributed over two rows 463, 464. The light sources 100 are at least partially embedded in a light-transmitting material 445, such as silicone. Scattering particles (not shown) may be included in the silicone. Reference number 440 indicates an intermediate layer (not yet an intermediate layer here, see FIG. 1b), which comprises two separate parts, each of which comprises (part of) a thermally conductive element 450. The thermally conductive element may comprise one or more parts, which may optionally be functionally combined (e.g. be part of the same monolithic thermally conductive element), the parts being respectively indicated with reference numbers 451 and 452.

[0146] Embodiment III (C2) shows a schematic representation of an embodiment in which the third light source 130, the fourth light source 140 and the fifth light source 150 are arranged over three different rows 463, 464, 465. The light sources 100 are at least partially embedded in a light-transmitting material 445, such as silicone. Scattering particles (not shown) may be included in the silicone. Reference number 440 indicates an intermediate layer (not yet an intermediate layer here, see FIG. 1b), which comprises an integral element comprising a thermally conductive element 450 (and which may comprise holes (not shown, see FIG. 1d)).

[0147] Thus, in embodiments II and III, the third light source 130, the fourth light source 140, and the fifth light source 150 are encapsulated by the same encapsulant.

[0148] Reference numeral 1120 denotes a second filament surface of the LED filament 1100 .

[0149] The reference symbol L1 denotes the length of the LED filament.

[0150] Figure 1b shows two schematic embodiments of the combination of the embodiments shown in Figure 1a: embodiment I shows a schematic sandwich configuration 400 obtained when combining embodiments I (W) and II (C1) of Figure 1a, and embodiment II shows a schematic sandwich configuration 400 obtained when combining embodiments I (W) and III (C2) of Figure 1a.

[0151] Thus, embodiments I and II of FIG. 1b (and FIG. 1c, see further below) diagrammatically illustrate an embodiment of an LED filament device 1000 comprising a first LED filament surface 1110, a second LED filament surface 1120, an intermediate layer 440, and a plurality of light sources 100.

[0152] In particular, in an embodiment, the first light source 110 may be configured to generate a first white light 111 having a first correlated color temperature CCT1. In an embodiment, the first light source 110 is associated with the first filament surface 1110. In an embodiment, the second light source 120 may be configured to generate a second white light 121 having a second correlated color temperature CCT2. In an embodiment, the second light source 120 is associated with the first filament surface 1110. In an embodiment, CCT2-CCT1≧500K. In an embodiment, the third light source 130 may be configured to generate a blue third light 131. In an embodiment, the third light source 130 is associated with the second filament surface 1120. In an embodiment, the fourth light source 140 may be configured to generate a green fourth light 141. In an embodiment, the fourth light source 140 is associated with the second filament surface 1120. In an embodiment, the fifth light source 150 may be configured to generate a red fifth light 151. In an embodiment, the fifth light source 150 is associated with the second filament surface 1120.

[0153] In an embodiment, the intermediate layer 440 may comprise a thermally conductive element 450 .

[0154] In an embodiment, the first LED filament surface 1110, the second LED filament surface 1120, and the intermediate layer 440 may be comprised by a sandwich configuration 400, with the intermediate layer 440 configured between at least a portion of the first LED filament surface 1110 and at least a portion of the second LED filament surface 1120.

[0155] The LED filament device 1000 may further comprise a light-transmitting material 445. In particular, the fourth light source 140 and the fifth light source 150, and optionally the third light source 130, may be configured to be at least partially embedded in the light-transmitting material 445. Furthermore, in an embodiment, the light-transmitting material 445 is transparent to the blue third light 131, the green fourth light 141, and the red fifth light 151. In particular, in an embodiment, the light-transmitting material 445 is translucent. In this way, the light of the light sources may be mixed.

[0156] In an embodiment, the light transmissive material 445 comprises a silicone material containing scattering particles. In an embodiment, the intermediate layer 440 comprises a metal layer. In an embodiment, the intermediate layer 440 comprises one or more of: (i) a copper layer, and (ii) an aluminum layer. In an embodiment, the metal layer and the light source 100 are not configured in conductive contact.

[0157] Referring to embodiments I and II of FIG. 1b, the intermediate layer 440 may be one or more of reflective and light absorbing to one or more of the blue third light 131 and the green fourth light 141, particularly to at least the former.

[0158] With reference to embodiment I of FIG. 1b (and in a variant see also embodiment II of FIG. 1b, FIG. 1d), in an embodiment, the LED filament device 1000 with the intermediate layer 440 may be configured such that a part of one or more of the first white light 111, the second white light 121 exits the sandwich configuration 400 via the second LED filament surface 1120. For this purpose, the intermediate layer 440, in particular the thermally conductive element 450, may comprise one or more openings 446 or a light-transmitting material.

[0159] With reference to the embodiment of FIG. 1b, two LED filaments 1100 may be applied. Thus, in an embodiment, the LED filament device 1000 comprises a first LED filament 1100' defining a first LED filament surface 1110 and a second LED filament 1100'' defining a second LED filament surface 1120. In particular, the first filament 1100 and the second filament 1100'' may be included by a sandwich configuration 400. Furthermore, an intermediate layer 440 may be configured between at least a portion of the first LED filament surface 1110 and at least a portion of the second LED filament surface 1120. In particular, the first LED filament 1100' and the second LED filament 1100'' comprise a support 1115, at least a portion of each of which is optically transparent to one or more of the first white light 111 and the second white light 121. In an embodiment, the intermediate layer 440 is configured between a portion of the first LED filament 1100' and a portion of the second LED filament 1100''.

[0160] In particular, in an embodiment, CCT1 is selected from a range of up to 2400 K, and CCT2 is selected from a range of at least 2700 K. In an embodiment, CCT1 is selected from a range of up to 1900-2400 K, and CCT2 is selected from a range of 2700-6500 K, and CCT2-CCT1≧1000 K.

[0161] Reference sign 300 refers to a control system. Thus, in an embodiment, the device 1000 may further comprise a control system 300. In particular, the control system 300 is configured to control the spectral power distribution of the device light 1001.

[0162] In an embodiment, the LED filament device 1000 is configured to generate a device light 1001 including one or more of the first white light 111, the second white light 121, the blue third light 131, the green fourth light 141, and the red fifth light 151. In an embodiment, the control system 300 is configured to control the first light source, the second light source, the third light source, the fourth light source, and the fifth light source individually. Furthermore, in an embodiment, the control system 300 may be configured to generate, in an operational mode, a first white device light 1001' including the first white light 111 and the second white light 121, and b a second white device light 1001'' including the blue third light 131, the green fourth light 141, and the red fifth light. In an embodiment, the second white device light 1001'' has a color point above the blackbody locus.

[0163] Furthermore, in an embodiment, the device 1000, more particularly the LED filament 1100, may comprise at least five of each of the first light source 110, the second light source 120, the third light source 130, the fourth light source 140, and the fifth light source 150, each of the first light source 110, the second light source 120, the third light source 130, the fourth light source 140, and the fifth light source 150 may comprise a solid-state light source 10. In an embodiment, the first light source 110 and the second light source 120 may be arranged in two parallel rows 461, 462, and the third light source 130, the fourth light source 140, and the fifth light source 150 may be arranged in two or three parallel rows 463, 464, 465.

[0164] With reference to FIG. 1c, embodiment I shows a schematic cross-section in the plane of the LED filament 1100, and embodiment II shows a schematic cross-section perpendicular to the plane of the LED filament 1100. Embodiments III and IV show schematic embodiments in which this LED filament is folded to provide a surface, in fact two LED filament surfaces, with the light source 100 and an intermediate layer 440 configured between the two LED filament surfaces. In fact, the support 1115 is folded at both the right and left ends (see embodiment II), and the expected sandwich configuration is obtained in embodiments III and IV (including the intermediate layer 440). Thus, in the embodiment, the LED filament device 1000 comprises an LED filament 1100, which is folded in half to define a first LED filament surface 1110 and a second LED filament surface 1120 configured opposite each other. In particular, the intermediate layer 440 is configured between at least a portion of the first LED filament surface 1110 and at least a portion of the second LED filament surface 1120.

[0165] Further, referring to FIG. 1c, in an embodiment, the LED filament 1000 comprises a support 1115, at least a part of which is optically transparent to one or more of the first white light 111 and the second white light 121. In an embodiment, the intermediate layer 440 is arranged between a portion of the first LED filament surface 1110 and a portion of the second LED filament surface 1120. More specifically, the intermediate layer may be arranged between two portions of the LED filament 1100, indicated by references P1110 and P1120. In this schematic illustrated embodiment, the portion P1110 may effectively comprise two portions. However, other solutions and configurations of the light source 100 may also be possible. The folded support 1115 may, in an embodiment, comprise one or two bends. FIG. 1c illustrates a schematic embodiment with two bends.

[0166] FIG. 1d shows two embodiments of the intermediate layer 440 in a schematic way. In particular, the intermediate layer is an elongated layer with a length L2 that may be in the range of 85-115%, in particular 85-100%, of the length L1 of the LED filament. Here, the intermediate layer comprises one or more holes 446 or a light-transmitting material. In particular, the intermediate layer may be provided by providing two or more parts and providing a light-transmitting material or holes therein, for example between the two parts. In these embodiments, by way of example, the intermediate layer 440 is an elongated layer comprising a first thermally conductive element part 451 and a second thermally conductive element part 452 and having one or more openings 453 between the first thermally conductive element part 451 and the second thermally conductive element part 452.

[0167] Figure 1e shows diagrammatically another solution with a single-sided LED filament having a first light source 110, a second light source 120 and a fourth light source 140. However, this solution has a substantially smaller color gamut than the solutions shown diagrammatically in figures 1a-1c.

[0168] 1f shows diagrammatically in embodiment I a solution in which the third light source 130 is based on solid-state light sources 10, which are embedded in the light-transmitting material 445, such that the external light source, or more particularly also the solid-state light sources, may be embedded in the light-transmitting material 445, but substantially in another body of the light-transmitting material 445. Thus, at least two bodies of light-transmitting material may be provided, which may further prevent crosstalk of the third light 131 to the other side (here from the second side 1120 to the first side 1110).

[0169] FIG. 1f shows an embodiment of an LED filament device 1000 comprising (i) a first LED filament surface 1110, (ii) a second LED filament surface 1120, (iii) an intermediate layer 440, and (iv) a plurality of light sources 100 in embodiment II. In the embodiment, a first set of light sources 100 is associated with the first filament surface 1110, and at least a first subset of these light sources 100 of the first set is configured to generate light 101, and the light 101 of this first subset of light sources is white light. Furthermore, in the embodiment, a second set of light sources 100 is associated with the second filament surface 1120, and at least a second subset of these light sources 100 of the second set is configured to generate light 101, and the light 101 of this second subset of light sources is a second colored light of the colored lights. Still further, in an embodiment, at least a third subset of these light sources 100 of the second set is configured to generate 101, the light 101 of this third subset of light sources being a third colored light of the colored light having a different spectral power distribution than the light of this second subset of light sources. Still further, in an embodiment, the first LED filament surface 1110, the second LED filament surface 1120, and the intermediate layer 440 are included by a sandwich configuration 400, the intermediate layer 440 being configured between at least a portion of the first LED filament surface 1110 and at least a portion of the second LED filament surface 1120. Furthermore, in an embodiment, the intermediate layer 440 comprises a first thermally conductive element portion 451 and a second thermally conductive element portion 452, and has one or more openings 453 between the first thermally conductive element portion 451 and the second thermally conductive element portion 452.

[0170] Referring also to FIG. 2 and also to FIGS. 1a-1c, in an embodiment, in an operational mode, the control system 300 is configured to generate a device light 1001 including (a) one or more of a first white light 111 and a second white light 121, and (b) one or more of a blue third light 131, a green fourth light 141, and a red fifth light, while maintaining a distance to the blackbody locus of up to 10 SDCM.

[0171] 3 also shows, in a schematic manner, an embodiment of a lighting system 1200 comprising the LED filament device 1000. The lighting device 1200 may be a retrofit lamp. Furthermore, an embodiment is shown in which the filament 1100 has a spiral or helical shape.

[0172] 3, the LED filament device 1000 is configured to generate an LED filament device light 1001. Thus, the lighting device 1200 may further comprise a control system 300 configured to control one or more of the spectral power distribution, color rendering index, correlated color temperature, and color point of the filament device light 1001 by individually controlling one or more of the first light source 110, the second light source 120, and one or more of the third light source 130, the fourth light source 140, the fifth light source 150, the sixth light source, and optionally further light sources.

[0173] The lighting device 1200 may comprise a light-transmitting envelope surrounding at least a portion of the LED filament device 1000.

[0174] Figure 4 shows, in a schematic manner, an embodiment of a luminaire 2 comprising a light generation system 1000 as described above. Reference number 301 indicates a user interface, which may be functionally coupled to a control system 300, which is included by or functionally coupled to the light generation system 1000. Figure 5 also shows, in a schematic manner, an embodiment of a lamp 1 comprising the light generation system 1000. Reference number 3 indicates a projection device or projection system, which may be used to project an image on a wall or the like, which may also comprise the light generation system 1000. The lamp or luminaire or projector device is also indicated herein as lighting device 1200.

[0175] The term "plurality" refers to two or more. The terms "substantially" or "essentially" and similar terms herein will be understood by those skilled in the art. The terms "substantially" or "essentially" may also include embodiments with "entirely", "completely", "all", etc. Thus, in embodiments, the adjectives substantially or essentially may also be omitted. Where applicable, the terms "substantially" or "essentially" may also relate to 90% or more, including 100%, such as 95% or more, particularly 99% or more, and even more particularly 99.5% or more. The term "comprises" also includes embodiments where the term "comprises" means "consists of".

[0176] The term "and / or" specifically refers to one or more of the items mentioned before and after "and / or." For example, the phrase "item 1 and / or item 2" and similar phrases may refer to one or more of items 1 and 2. The term "comprising" may, in one embodiment, refer to "consisting of," but in another embodiment may also refer to "including at least the defined species, and optionally one or more other species."

[0177] Moreover, the terms first, second, third, etc., in the specification and claims are used to distinguish between similar elements and are not necessarily used to describe a sequential or chronological order, and the terms so used are interchangeable under appropriate circumstances, with it being understood that the embodiments of the invention described herein are capable of operation in other orders than those described or illustrated herein.

[0178] As used herein, a device, apparatus, or system may be described, among other things, in operation. As will be apparent to one of ordinary skill in the art, the present invention is not limited to methods of operation or to devices, apparatus, or systems in operation.

[0179] It should be noted that the above-described embodiments are illustrative rather than limiting of the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims.

[0180] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0181] Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Unless the context clearly requires otherwise, throughout the specification and claims, the words "comprise", "comprising", and the like, are to be interpreted in an inclusive sense, i.e., "including, but not limited to", rather than an exclusive or exhaustive sense.

[0182] The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0183] The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device, apparatus or system claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain means are recited in mutually different dependent claims does not indicate that a combination of these means cannot be used to advantage.

[0184] The present invention also provides a control system that may control a device, apparatus or system or that may perform the methods or processes described herein. Still further, the present invention also provides a computer program product operatively coupled to or contained by a device, apparatus or system, which when executed on a computer controls one or more controllable elements of such a device, apparatus or system.

[0185] The invention further applies to a device, an apparatus or a system comprising one or more of the features described in the present specification and / or shown in the accompanying drawings.The invention further relates to a method or process comprising one or more of the features described in the present specification and / or shown in the accompanying drawings.

[0186] The various aspects discussed in this patent may be combined to provide additional advantages. Moreover, those skilled in the art will appreciate that embodiments may be combined, and that three or more embodiments may be combined. Moreover, some of the features may form the basis for one or more divisional applications.

Claims

1. 1. An LED filament device comprising: (i) a first LED filament surface; (ii) a second LED filament surface; (iii) an intermediate layer; and (iv) a plurality of light sources, a first light source configured to generate a first white light having a first correlated color temperature CCT1, the first light source being associated with the first filament face; a second light source configured to generate a second white light having a second correlated color temperature CCT2, said second light source being associated with said first filament surface, CCT2-CCT1≧500K; a third light source configured to generate a third light of a blue color, the third light source associated with the second filament face; a fourth light source configured to generate a fourth light of a green color, the fourth light source associated with the second filament face; a fifth light source configured to generate a fifth light of a red color, said fifth light source associated with said second filament face; the intermediate layer comprises a thermally conductive element; the first LED filament surface, the second LED filament surface, and the intermediate layer are included by a sandwich configuration, the intermediate layer being configured between at least a portion of the first LED filament surface and at least a portion of the second LED filament surface; an LED filament device, wherein the first filament surface comprises only the first light source and the second light source, and the second LED filament surface comprises only the third light source, the fourth light source, and the fifth light source.

2. 2. The LED filament device of claim 1, further comprising a light-transmitting material, wherein the fourth light source and the fifth light source, and optionally the third light source, are configured to be at least partially embedded in the light-transmitting material, the light-transmitting material being transparent to the blue third light, the green fourth light, and the red fifth light, and the light-transmitting material being translucent.

3. 3. An LED filament device as claimed in claim 1 or 2, wherein the intermediate layer comprises a metal layer or a carbon layer.

4. 4. The LED filament device of claim 3, wherein the intermediate layer comprises one or more of: (a) a copper layer; and (b) an aluminum layer, and the metal layer and the light source are not configured in conductive contact.

5. 3. The LED filament device according to claim 1, wherein the intermediate layer is one or more of (i) reflective and (ii) light absorbing with respect to one or more of (a) the blue third light and (b) the green fourth light, and the LED filament device comprising the intermediate layer is configured such that a portion of one or more of the first white light and the second white light escapes the sandwich configuration through the second LED filament surface.

6. 3. The LED filament device of claim 1 or 2, wherein the LED filament device comprises an LED filament configured to be folded in half to define the first LED filament surface and the second LED filament surface configured opposite each other.

7. 6. The LED filament device of claim 5, wherein the LED filament comprises a support, at least a portion of the support being optically transparent to one or more of the first white light and the second white light, and the intermediate layer is configured between a portion of the first LED filament surface and a portion of the second LED filament surface.

8. 3. The LED filament device of claim 1, comprising a first LED filament defining the first LED filament surface and a second LED filament defining the second LED filament surface, the first filament and the second filament being contained by the sandwich configuration.

9. The LED filament device of claim 5, wherein the first LED filament and the second LED filament have supports, at least a portion of each of the supports being optically transparent to one or more of the first white light and the second white light, and the intermediate layer is configured between a portion of the first LED filament and a portion of the second LED filament.

10. 6. The LED filament device of claim 5, wherein the intermediate layer is an elongated layer comprising a first thermally conductive element portion and a second thermally conductive element portion and having one or more openings between the first thermally conductive element portion and the second thermally conductive element portion.

11. 3. The LED filament device according to claim 1 or 2, wherein CCT1 is selected from the range of 1900 to 2400K at most, CCT2 is selected from the range of 2700 to 6500K, and CCT2-CCT1≧1000K.

12. 3. The LED filament device of claim 1 or 2, further comprising a control system, the LED filament device configured to generate device light including one or more of the first white light, the second white light, the blue third light, the green fourth light, and the red fifth light, and the control system configured to control a spectral power distribution of the device light.

13. 13. The LED filament device of claim 12, wherein the control system is configured to individually control the first light source, the second light source, the third light source, the fourth light source, and the fifth light source.

14. 13. The LED filament device of claim 12, wherein the control system is configured in an operational mode to generate (a) a first white device light including a first white light and a second white light, and (b) a second white device light including a blue third light, a green fourth light, and a red fifth light, the second white device light having a color point above the blackbody locus.

15. 3. A lighting device, the lighting device being a retrofit lamp, comprising a light-transmitting envelope surrounding at least a portion of the LED filament device according to claim 1 or 2.

Images