CCT controllable LED lamp filament device with LED lamp filament with same color and appearance as that of light source in closed state

Abstract

The present disclosure describes a light emitting diode (LED) filament arrangement (100) for providing device light, the LED filament arrangement (100) comprising: a first LED filament (110) configured to emit first LED filament light having a first correlated color temperature CCT1; a second LED filament (160) configured to emit second LED filament (160) light having a second correlated color temperature CCT2; and a controller (210) for individually controlling the first LED filament light emitted by the first LED filament (110) and the second LED filament (160) light emitted by the second LED filament (160) such that the correlated color temperature of the device light is variable. The present disclosure also describes an LED filament lamp (220) comprising the LED filament arrangement (100), wherein the LED filament lamp (220) further comprises a housing (230) at least partially surrounding the first LED filament and the second LED filament (160), and a cover (240) for electrically and mechanically connecting the LED filament lamp (220) to a lamp socket. The present disclosure also describes a luminaire (250) comprising an LED filament arrangement (100) or an LED filament lamp (220).

Description

Technical Field

[0001] The present invention generally relates to LED filament devices. In particular, the present invention relates to LED filament devices for providing light with an adjustable correlated color temperature. Background Art

[0002] The field of lighting technology has been developing rapidly with the introduction of new technologies such as light emitting diodes (LEDs). The field is undergoing constant changes and continues to gain attention. Compared with traditional light sources such as incandescent, fluorescent, and neon lamps, devices or equipment containing LEDs have many advantages, such as greater flexibility and control, more compact design, and / or lower power consumption. In particular, traditional light sources are being rapidly replaced by LED-based lighting solutions.

[0003] Devices or apparatuses such as LED filament lamps or luminaires may be used to provide light with an adjustable correlated color temperature (CCT). A device with an adjustable CCT may be obtained by providing a plurality of LED filaments, wherein each LED filament is configured to provide light with a different CCT. A problem with the above is that the device will include different LED filaments having different off-state colors and thus appear visually unpleasing.

[0004] Therefore, an object of the present invention is to provide a lighting device which can overcome the above-mentioned disadvantages.

[0005] WO 2020 / 260197 relates to a lighting device comprising a first elongated LED filament and a second elongated LED filament. The lighting device further comprises an at least partially light-transmissive housing, the housing at least partially enclosing at least the first LED filament and the second LED filament, and a base to which the at least partially light-transmissive housing is mounted. The first LED filament is configured to emit light having a different color temperature than the second LED filament. In addition, the second LED filament is at least partially bent so that it defines at least a portion of a volume contour. The first LED filament is at least partially arranged within the volume. Summary of the invention

[0006] A first aspect of the present invention provides a light emitting diode (LED) filament device for providing device light, the LED filament device comprising: a first LED filament configured to emit a first LED filament light having a first correlated color temperature (CCT1); the first LED filament comprising a first carrier; a plurality of first LEDs arranged on the first carrier, wherein each first LED is configured to emit a first LED light having a first peak wavelength (λ1); and a first package encapsulating the plurality of first LEDs and at least partially covering the first carrier; wherein the first package comprises a first luminescent material configured to at least partially convert the first LED light into a first converted light, and wherein the first package has a first light source off state color appearance (A1); a second LED filament configured to emit a second LED filament light having a second correlated color temperature (CCT2); the second LED filament comprising a second A carrier; a plurality of second LEDs arranged on the second carrier, wherein each second LED is configured to emit a second LED light having a second peak wavelength λ2; and a second package encapsulating the plurality of second LEDs and at least partially covering the second carrier, wherein the second package comprises a second luminescent material configured to at least partially convert the second LED light into a second converted light, wherein the second package has a second light source off-state color appearance A2, and a controller for separately controlling the first LED filament light emitted by the first LED filament and the second LED filament light emitted by the second LED filament so that the device light can vary in correlated color temperature, wherein λ1 is in the range of 430-494, wherein λ2=487+ / -7nm, wherein CCT1≤CCT2-500K, and wherein A1 and A2 are the same.

[0007] An LED filament device may be employed to provide device light with an adjustable CCT, wherein the LED filaments of the LED filament device have the same off-state color appearance. According to testing, λ1 and λ2=487+ / -7nm in the range of 430-494 allow for the generation of melanopic light while providing device light with a high CCT. The LED filament device also allows the use of similar materials as the first package and the second package, so that the LED filaments of the LED filament device have the same off-state color appearance.

[0008] In one embodiment of the present invention, λ1=450+ / -20nm, λ2=487+ / -7nm, λ2-λ1≥20nm. Using these specific wavelengths enables the use of similar phosphors and phosphor ratios, so that the LED filaments of the LED filament device have the same off-state color appearance. Using these specific wavelengths can produce good light quality because two different types of blue light can be used, and can also produce controllable melanopsin light while providing device light with high CCT.

[0009] In another embodiment of the present invention, λ1 = 487 + / - 7 nm, λ2 = 487 + / - 7 nm. Using these specific wavelength ranges is advantageous because it enables the first luminescent material and the second luminescent material to be similar or identical, thereby enabling the LED filaments of the LED filament device to have the same off-state color appearance. Using these specific wavelength ranges enables both the first LED filament and the second LED filament to emit white light over a wide range of correlated color temperatures and also to produce melanopic light at low CCT.

[0010] In another embodiment of the present invention, the first package has a first thickness T1 and a first luminescent material concentration C1, wherein the second package has a second thickness T2 and a second luminescent material concentration C2, wherein T2≤0.8T1 and / or C2≤0.8C1. The effect obtained is that different CCT1 and CCT2 can be selected to provide a device light with adjustable CCT.

[0011] In another embodiment of the present invention, the first luminescent material includes a green phosphor and / or a yellow phosphor and a red phosphor, and the second luminescent material includes a green phosphor and / or a yellow phosphor and a red phosphor. Thus, the luminescence of the first luminescent material and the second luminescent material can be selected to at least partially determine CCT1 and CCT2.

[0012] In another embodiment of the present invention, the green phosphor and / or yellow phosphor of the first luminescent material and the second luminescent material are the same, and optionally, the red phosphor of the first luminescent material and the second luminescent material are the same. The effect obtained here is that the first LED filament and the second LED filament obtain the color appearance of the light source off state.

[0013] In another embodiment of the present invention, the green phosphor and / or the yellow phosphor has a lower excitation intensity at the second peak wavelength λ2 than at the first peak wavelength λ1. The excitation intensities of the first luminescent material and the second luminescent material can be selected to at least partially determine the difference between CCT1 and CCT2, so that the CCT of the device light can be adjusted.

[0014] In another embodiment of the present invention, the difference in excitation intensity at the first peak wavelength and the second peak wavelength is at least 20% of the peak excitation intensity of the green phosphor and / or the yellow phosphor. Therefore, the excitation intensity of the first luminescent material and the second luminescent material can have a certain amplitude so that CCT1 and CCT2 can be different.

[0015] In another embodiment of the present invention, CCT1 ≤ 2500 K and CCT2 ≥ 2700 K, preferably, CCT1 is in the range of 800 K-2400 K. The difference between CCT1 and CCT2 enables a large change in the CCT of the device light.

[0016] In another embodiment of the present invention, the device light is configured to be adjusted between a third correlated color temperature CCT3 and a fourth correlated color temperature CCT4, wherein CCT3≤2500K and CCT4≥2700K, and CCT3≤CCT4-500K. The difference between CCT3 and CCT4 has been found by developers to be preferred in a wide range of applications, such as in LED filament lamps and luminaires.

[0017] In another embodiment of the present invention, CCT1 ≤ 2300K, CCT3 ≤ 2300K, CCT2 ≥ 3000K, and CCT4 ≥ 3000K. The difference between CCT3 and CCT4 has been found by investors to be preferred in a wide range of applications, such as in LED filament lamps and luminaires.

[0018] In another embodiment of the present invention, any one or more of the first luminescent material and the second luminescent material include a luminescent material of the A3B5O12:Ce type, wherein A includes one or more of Y, La, Gd, Tb and Lu, wherein B includes one or more of Al, Ga, In and Sc; wherein the device light is white light with a correlated color temperature in the range of 1800K-6500K and a color rendering index of at least 80. Such selection of the first luminescent material and the second luminescent material enables a high excitation probability and a desired wavelength distribution of the converted light.

[0019] In another embodiment of the present invention, any one or more of the first luminescent material and the second luminescent material comprises a KSiF phosphor.Such a selection of the first luminescent material and the second luminescent material enables a high excitation probability and an ideal wavelength distribution of the converted light.

[0020] A second aspect of the present invention provides an LED filament lamp, comprising an LED filament device, the LED filament lamp further comprising a housing at least partially surrounding a first LED filament and a second LED filament, and a cover for electrically and mechanically connecting the LED filament lamp to a lamp socket, and further comprising an antenna for wirelessly controlling a controller. The LED filament lamp can be employed to provide light with an adjustable CCT, and wherein the LED filaments of the LED filament lamp have the same off-state color appearance.

[0021] A third aspect of the present invention provides a lamp comprising an LED filament device or an LED filament lamp. The lamp can be used to provide light with an adjustable CCT, and the LED filament of the lamp has the same off-state color appearance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiments of the invention.

[0023] Figure 1 The LED filament device is schematically illustrated, comprising a first LED filament, a second LED filament and a controller,

[0024] Figure 2 A first LED filament and a second LED filament are schematically illustrated, wherein each LED filament comprises a carrier, a plurality of LEDs and a package, wherein a thickness of the package of the first LED filament is smaller than a thickness of the package of the second LED filament,

[0025] Figure 3 schematically illustrates an LED filament lamp comprising an LED filament device,

[0026] Figure 4 The relative intensities of the first LED, the second LED and the blue LED and the excitation spectrum of the YAG:Ce type phosphor are schematically illustrated.

[0027] Figure 5 schematically illustrates a CIE color space chromaticity diagram showing a correlated color temperature of a first LED filament and a correlated color temperature of a second LED filament, and

[0028] Figure 6 A lamp comprising an LED filament arrangement is schematically illustrated. DETAILED DESCRIPTION

[0029] In the following, general embodiments of the invention as well as specific exemplary embodiments will be described. Reference will be made to the accompanying drawings. It should be noted, however, that the drawings are only exemplary embodiments and that other features and embodiments are also possible within the scope of the invention. Furthermore, references to "a" or "an" or the like should not be construed as excluding the plurality, and the term "disclosure" may be used interchangeably with the term "invention" herein.

[0030] Unless otherwise defined, all professional terms, symbols and other scientific terms or terminology used herein shall have the meanings commonly understood by those skilled in the art. However, certain professional terms, symbols and other scientific terms or terminology may be specifically defined as described below.

[0031] The invention relates to an LED filament device, an LED filament lamp comprising the LED filament device, and a lamp comprising the LED filament device.

[0032] Reference Figure 1 According to the present invention, the LED filament device 100 includes a first LED filament 110, a second LED filament 160 and a controller 210. As shown, the first LED filament 110 and the second LED filament 160 can be connected to the controller 210, for example, via direct or indirect electronic connection.

[0033] The first LED filament is configured to emit a first LED filament light having a first correlated color temperature CCT1, and the second LED filament is configured to emit a second LED filament light having a second correlated color temperature CCT2. The controller is configured to control the first LED filament light and the second LED filament light individually, so that the LED filament device as a whole can emit device light. By controlling the intensity and correlated color temperature of the first LED filament light and the second LED filament light, the correlated color temperature CCT of the device light can be changed. The controller itself can be, for example, pre-programmed or controlled via, for example, an external switch, an external control unit or the like. The controller can, for example, include or be connected to an antenna for wireless communication with an external controller unit.

[0034] See also Figure 2 and Figure 3 According to the present invention, the first LED filament 110 includes a first carrier 120, a plurality of first LEDs 130 and a first encapsulation body 140, while the second LED filament 160 includes a second carrier 170, a plurality of second LEDs 180 and a second encapsulation body 190. The plurality of first LEDs 130 and the second LEDs 180 are arranged, for example, periodically on the first carrier 120 and the second carrier 170, respectively. The encapsulation body 140, 190 of each filament 110, 160 is arranged to encapsulate the plurality of LEDs 130, 180 arranged on the carrier 120, 170 of the filament 110, 160 and at least partially cover the carrier 120, 170. If any light emitted by the LED must pass through the encapsulation body 140, 190 before leaving the LED filament 110, 160, the LEDs 130, 180 arranged on the LED filament 110, 160 can be regarded as encapsulated by the encapsulation body. The LEDs 130, 180 on the carrier 120, 170 and encapsulated by the encapsulation body 140, 190 may thus generally be in contact with the carrier 120, 170 and the encapsulation body 140, 190. In certain embodiments, the first LED filament may include only the first LED. In certain embodiments, the second LED filament may include only the second LED.

[0035] like Figure 1 or Figure 2As schematically shown in FIG. 1 , each carrier 120, 170 may be an elongated body, for example, with a longitudinal length in the range of 1-1 cm and a lateral width in the range of 1-1 mm. A plurality of first LEDs 130 and a second LED 180 are arranged on the first carrier 120 and the second carrier 170, respectively, for example, evenly distributed in the longitudinal direction of the elongated body of the relevant carrier 120, 170. For each carrier 120, 170, a plurality of LEDs 130, 180 may be connected to a power source via the carrier 120, 170, for example, via one or more electrical conductors of the carrier 120, 170 or by the carrier 120, 170 itself as a conductor. A person skilled in the art will recognize, with the knowledge of the present disclosure, that either or both of the first carrier 120 and the second carrier 170 may take various shapes, and that the arrangement of the LEDs 130, 180 on either carrier 120, 170 may vary. Either or both of the first carrier 120 and the second carrier 170 may, for example, be shaped as a spiral, an annular shape, etc.

[0036] The first package and the second package may include a first luminescent material and a second luminescent material, respectively, according to the present invention. The first luminescent material is configured to at least partially convert the first LED light into a first converted light, and the second luminescent material is configured to at least partially convert the second LED light into a second converted light. Each luminescent material may absorb at least a portion of the LED light from the LED packaged therein and re-emit the converted light in the form of luminescent radiation. The intensity and wavelength distribution of any converted light emitted by the package may depend on the properties of the LED light emitted by the packaged LED and the properties of the package. The properties of the LED light may include any one or more of the intensity and wavelength distribution. The properties of the package may include one or more of the thickness, transmittance and excitation intensity of the package. Figure 4 The relative intensity of the blue LED and the excitation spectrum of the YAG:Ce package are schematically illustrated. It can be seen here that the excitation spectrum is offset relative to the wavelength distribution of the blue LED. Figure 4 As schematically illustrated in , the first LED light and the second LED light may have peak wavelengths λ1 and λ2, where λ1 = 440 nm and λ2 = 487 nm.

[0037] The excitation intensity of the first package and the second package may depend, among other things, on the first luminescent material concentration Cl and the second luminescent material concentration C2, respectively. Therefore, Cl and C2 may be selected to at least partially determine the amount of the first converted light and the second converted light, respectively. According to a specific embodiment of the present disclosure, the first luminescent material concentration may be greater than the second luminescent material concentration. More preferably, the first luminescent material concentration and the second luminescent material concentration may be selected such that C2 ≤ 0.8C1. The latter may enable a larger amount of the first converted light relative to the second converted light and will shift the first filament light to the right of the CIE color space chromaticity diagram relative to the second filament light. The latter in Figure 5 Visualization.

[0038] According to the present disclosure, the light emitted by the LED filament will be a combination of the LED light and the converted light. Therefore, the CCT of the light emitted by the LED filament can be selected by selecting any one or more parameters that affect the conversion characteristics of the LED light or the package. Similarly, the device light emitted by the LED filament device is a combination of the first LED filament light and the second LED filament light. Therefore, the device light can be selected by defining any one or more parameters that affect any one or more of the first LED light, the second LED light, the conversion characteristics of the first package, and the conversion characteristics of the second package. Therefore, the CCT of the LED filament device depends on CCT1, CCT2, and the intensity of the first LED filament light and the second LED filament light.

[0039] According to the present invention, each first LED is configured to emit a first LED light having a first peak wavelength λ1, and each second LED is configured to emit a second LED light having a second peak wavelength λ2. Here, λ1 may be different from λ2. Each first LED may typically be an LED configured to emit a first LED light having a first peak wavelength λ1, λ1 being in the range of 430-494nm, and each second LED may typically be an LED configured to emit a second LED light having a second peak wavelength λ2=487+ / -7nm. In other words, each first LED may be configured to emit light in the blue-cyan range, and each second LED may be configured to emit cyan light. The term peak wavelength may be used interchangeably with the term dominant wavelength. λ2 is preferably selected so that λ2=487+ / -6nm, more preferably λ2=487+ / -5nm, and most preferably, 487+ / -4nm.

[0040] In one embodiment of the present invention, λ1=450+ / -20nm, and λ2-λ1≥20nm. It has been found that the wavelengths allow the generation of melanopic light while providing device light with a high CCT. Melanopic light can be regarded as light in the wavelength range of 475-500nm. The difference between λ1 and λ2 is at least 20nm, i.e. λ2-λ1≥20nm, which is particularly preferred for achieving device light with a high CCT and additional melanopic light. In a preferred embodiment, λ2-λ1≥25nm, more preferably ≥30nm, most preferably ≥35nm. For λ1, preferably λ1=450+ / -15nm, more preferably λ1=450+ / -12nm, most preferably λ1=445+ / -10nm.

[0041] In a specific embodiment of the present invention, λ1=487+ / -7nm and λ2=487+ / -7nm. Selecting λ1=487+ / -7nm and λ2=487+ / -7nm enables both the first LED and the second LED to emit the same light. The first luminescent material and the second luminescent material may be the same material, for example the first luminescent material and the second luminescent material may include the same ratio between green phosphor and red phosphor, or the same ratio between yellow phosphor and red phosphor. Therefore, A1 and A2 may be the same. The thickness and / or concentration of the phosphor between the first LED filament and the second LED filament may be different so as to provide a difference between CCT1 and CCT2. Selecting λ1=487+ / -7nm and λ2=487+ / -7nm enables both the first LED filament and the second LED filament to emit white light with a wide range of correlated color temperatures.

[0042] like Figure 5 As schematically visualized in FIG. 1 , the difference between λ1 and λ2 may result in the first LED filament light having CCT1 and the second LED filament light having CCT2. Therefore, a controller may be employed to adjust the intensity of the first LED and the intensity of the second LED to adjust the ratio between the first LED filament light having CCT1 and the second LED filament light having CCT2. Therefore, a controller may be used to adjust the CCT of the device light because the combination of the first LED filament light and the second LED filament light constitutes the device light. For example, the intensity of either the first LED and / or the second LED may be adjusted by adjusting the power delivered to the first LED and / or the second LED.

[0043] According to the invention, the difference between CCT1 and CCT2 may generally be selected such that CCT1 ≤ CCT2 - 500K. The difference is preferred so as to provide a minimum adjustment of the CCT of the LED filament arrangement. Preferably CCT1 ≤ CCT2 - 1000K, more preferably CCT1 ≤ CCT2 - 1500K, most preferably CCT1 ≤ CCT2 - 2000K.

[0044] In a specific embodiment of the present invention, CCT1 and CCT2 may be selected such that CCT1 ≤ 2500K and CCT2 ≥ 2700K. The device light may be configured to adjust between a third correlated color temperature CCT3 and a fourth correlated color temperature CCT4. CCT3 and CCT4 may be selected such that CCT3 ≤ 2500K, CCT4 ≥ 2700K, and CCT3 ≤ (CCT4 - 500K). In another embodiment, CCT1, CCT2, CCT3, and CCT4 may be selected such that CCT1 ≤ 2300K, CCT3 ≤ 2300K, CCT2 ≥ 3000K, and CCT4 ≥ 3000K.

[0045] refer to Figure 2 , the first encapsulant 140 may have a first thickness T1, and the second encapsulant 190 may have a second thickness T2. The thickness of any encapsulant 140, 190 may be understood herein as the thickness of the encapsulant 140, 190 on any LED 130, 180, i.e., the thickness of the encapsulant 140, 190 is the shortest distance that the light from the encapsulated LED 130, 180 of the filament 110, 160 must travel in the encapsulant 140, 190 before leaving the filament 110, 160. According to one embodiment of the present invention, T1 and T2 may be selected such that T2 ≤ 0.8T1. It has been found that such a thickness difference can adequately adjust the CCT of the device light.

[0046] The first package and the second package may have a first and a second light source off state color appearance, respectively, according to the present disclosure. The first and second light source off state color appearances may be generally referred to herein as A1 and A2. The light source off state color appearance of any package may be determined, for example, by the fluorescence and reflectivity of the package. The light source off state color appearance of a package may be defined, for example, by the peak wavelength of light emitted from the package. Using the latter definition, if the peak wavelength of light emitted from the first package in the off state is within 15 nm, preferably 10 nm, of the peak wavelength of light emitted from the second package, then A1 and A2 may be defined as the same herein. The light source off state color appearance of a package may also be defined using CIE xy parameters. Using the latter definition, if X A1 =X A2 ±1.0 and y A1 =y A2 ±1.0, then A1 and A2 can be defined as the same; if X A1 =X A2 ±0.5 and y A1 =y A2±0.5, then A1 and A2 can be defined as being the same. When the first package and the second package have the same color (usually orange), A1 can alternatively be considered to be the same as A2. The first package and the second package can also additionally have the same hue, more particularly, they can have the same chromaticity, chroma and / or saturation.

[0047] According to an embodiment of the present invention, any one or more of the first luminescent material and the second luminescent material may each include a green phosphor and / or a yellow phosphor and a red phosphor. In other words, any one or more of the first luminescent material and the second luminescent material may each include a green phosphor and a red phosphor, a yellow phosphor and a red phosphor, or a green phosphor, a yellow phosphor and a red phosphor. The green phosphor and / or the yellow phosphor of the first luminescent material and the green phosphor and / or the yellow phosphor of the first luminescent material may be different or the same. The red phosphor of the first luminescent material and the red phosphor of the second luminescent material may be different or the same in addition or optionally. The green phosphor and / or the yellow phosphor may, for example, have an excitation intensity lower at λ2 than at λ1. In a specific embodiment, the difference in excitation intensity at the first peak wavelength and the second peak wavelength may be at least 20% of the peak excitation intensity of the green phosphor and / or the yellow phosphor.

[0048] According to an embodiment of the present invention, any one or more of the first luminescent material and the second luminescent material may include A3B5O 12 : Ce type luminescent material. A here may include one or more of Y, La, Gd, Tb and Lu, B may include one or more of Al, Ga, In and Sc, and O is oxygen. Any one or more of the first luminescent material and the second luminescent material may include, for example, yttrium aluminum garnet Y3Al5O 12 Or gadolinium aluminum garnet Gd3Al5O 12 . In another example, the first luminescent material and / or the second luminescent material may include a KSiF phosphor. In another example, the first luminescent material and / or the second luminescent material may include a LuAG phosphor. Those skilled in the art familiar with the present invention will recognize that the first luminescent material and the second luminescent material may be selected, optionally in combination with λ1 and λ2, to determine a range of correlated color temperatures over which the LED filament device may vary. According to any embodiment of the present invention, the device light may be generally white light having a correlated color temperature in the range of 1800K-6500K and a color rendering index of at least 80.

[0049] The LED filament device 100 may generally be a part of an LED light bulb, an LED filament lamp 220 , a lamp fixture 250 , or the like. Figure 3An LED filament lamp 220 including the LED filament device 100 is schematically illustrated. The LED filament lamp 220 may also include a housing 230 at least partially surrounding the first LED filament 110 and the second LED filament 160 and a cover 240 for electrically and mechanically connecting the LED filament lamp 220 to a socket (e.g., a socket of the lamp 250). The housing 230 may be a transparent material (e.g., transparent ceramic) or a polymer. The cover 240 (sometimes also referred to as a base) may be, for example, an Edison screw, such as E27, E14, or the like. Figure 6 A lamp 250 including the LED filament device 100 is schematically illustrated. Those skilled in the art will appreciate that the lamp 250 may take a variety of shapes. Figure 6 As schematically shown, a plurality of LED filament arrangements 100 are included.

[0050] LED filament lamp 220 or lamps such as Figure 3 As shown, an antenna 260 is generally also included. Here, the antenna can be configured to wirelessly communicate with an external control unit or similar device to provide instructions to the controller 210 of the filament device 100. Therefore, the antenna 260 can be regarded as configured to control the controller 210.

Claims

1. A light emitting diode (LED) filament device (100) for providing device light, the LED filament device (100) comprising: A first LED filament (110) is configured to emit first LED filament light having a first correlated color temperature CCT1, wherein the first LED filament (110) comprises: a first carrier (120), a plurality of first LEDs (130) arranged on the first carrier (120), wherein each first LED (130) is configured to emit first LED light having a first peak wavelength λ1, and a first package body (140) encapsulating the plurality of first LEDs (130) and at least partially covering the first carrier (120), wherein the first package body (140) comprises a first luminescent material (150), the first luminescent material being configured to at least partially convert the first LED light into a first converted light, and wherein the first package body (140) has a first light source off state color appearance A1, A second LED filament (160) is configured to emit a second LED filament (160) light having a second correlated color temperature CCT2, wherein the second LED filament (160) comprises a second carrier (170), a plurality of second LEDs (180) arranged on the second carrier (170), wherein each second LED (180) is configured to emit second LED light having a second peak wavelength λ2, and a second package encapsulating the plurality of second LEDs (180) and at least partially covering the second carrier (170), wherein the second package comprises a second luminescent material (200), the second luminescent material being configured to at least partially convert the second LED light into a second converted light, and wherein the second package has a second light source off-state color appearance A2, and; A controller (210) for individually controlling the first LED filament light emitted by the first LED filament (110) and the second LED filament (160) light emitted by the second LED filament (160), so that the device light can be varied in correlated color temperature; Where λ1 is in the range of 430-494, where λ2 = 487 + / - 7 nm, where CCT1 ≤ (CCT2 - 500K), and where A1 and A2 are the same.

2. The LED filament device (100) according to claim 1, wherein λ1 = 450 + / - 20 nm, wherein λ2 = 487 + / - 7 nm, and wherein λ2 - λ1 ≥ 20 nm.

3. The LED filament device (100) according to claim 1, wherein λ1 = 487 + / - 7 nm, and wherein λ2 = 487 + / - 7 nm.

4. The LED filament device (100) according to any one of the preceding claims, wherein the first package (140) has a first thickness T1 and a first luminescent material (150) concentration C1, wherein the second package has a second thickness T2 and a second luminescent material (200) concentration C2, wherein T2≤0.8T1 and / or wherein C2≤0.8C1.

5. The LED filament device (100) according to any one of the preceding claims, wherein the first luminescent material (150) comprises a green phosphor and / or a yellow phosphor, and a red phosphor, and wherein the second luminescent material (200) comprises a green phosphor and / or a yellow phosphor, and a red phosphor.

6. The LED filament device (100) according to claim 5, wherein the green phosphor and / or the yellow phosphor of the first luminescent material and the second luminescent material (200) are the same, and optionally wherein the red phosphor of the first luminescent material and the second luminescent material (200) are the same.

7. The LED filament device (100) according to claim 5 or 6, wherein the green phosphor and / or the yellow phosphor has an excitation intensity at the second peak wavelength λ2 that is lower than the excitation intensity at the first peak wavelength λ1.

8. The LED filament device (100) according to any one of claims 5-7, wherein the difference in excitation intensity at the first peak wavelength and the second peak wavelength is at least 20% of the peak excitation intensity of the green phosphor and / or the yellow phosphor.

9. The LED filament device (100) according to any one of the preceding claims, wherein CCT1 ≤ 2500K and CCT2 ≥ 2700K, preferably, wherein CCT1 is in the range of 800K-2400K.

10. The LED filament device (100) according to any one of the preceding claims, wherein the device light is configured to be modulated between a third correlated color temperature CCT3 and a fourth correlated color temperature CCT4, wherein CCT3≤2500K and CCT4≥2700K, and CCT3≤(CCT4-500K).

11. The LED filament device (100) according to claim 10, wherein CCT1≤2300K, CCT3≤2300K, CCT2≥3000K and CCT4≥3000K.

12. The LED filament device (100) of any one of the preceding claims, wherein any one or more of the first luminescent material (150) and the second luminescent material (200) comprises a luminescent material of the A3B5O12:Ce type, wherein A comprises one or more of Y, La, Gd, Tb and Lu, and wherein B comprises one or more of Al, Ga, In and Sc; and wherein the device light is white light having a correlated color temperature in the range of 1800K-6500K and a color rendering index of at least 80.

13. The LED filament device (100) according to any one of the preceding claims, wherein any one or more of the first luminescent material (150) and the second luminescent material (200) comprises a KSiF phosphor.

14. An LED filament lamp (220), comprising the LED filament device (100) according to any one of the preceding claims, the LED filament lamp (220) further comprising a housing (230) at least partially surrounding the first LED filament and the second LED filament (160), and a cover (240) for electrically and mechanically connecting the LED filament lamp (220) to a socket of a lamp fixture (250), and further comprising an antenna (260) for wirelessly controlling the controller (210).

15. A lamp (250), comprising the LED filament device (100) according to any one of Claims 1 to 13 or the LED filament lamp (220) according to Claim 14.

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