Tunable light emitting device

Abstract

A light emitting device configured to tunably emit light having a total color temperature (CT tot ) of 2700 K to 6500 K, the light emitting device comprising: a carrier comprising a first major surface and an opposite second major surface; a first light source arranged on the first major surface and arranged to emit light having a first color temperature (CT1) tunably adjustable in a first range from a first low color temperature to a first high color temperature; a second light source arranged on the second major surface and arranged to emit light having a second color temperature (CT2) tunably adjustable in a second range from a second high temperature to a second low temperature; a controller configured to individually control the first and second light sources so as to tunably adjust CT1 and CT2 from a first state to a second state according to a preselected scheme by increasing CT1 and decreasing CT2 between the first and second states such that CT tot remains constant.

Description

Technical Field

[0001] This invention relates to a light-emitting device with tunable color temperature. Background Technology

[0002] Lamps, luminaires, or lighting equipment with controllable light sources such as light-emitting diodes (LEDs) can communicate with a controller or control unit. This may be particularly desirable for lamps capable of emitting different colors of light (such as multi-color filament lamps) to facilitate or allow adjustment of the color of the light emitted by the lamp. Additionally or alternatively, dimming of (multiple) light sources of the lighting equipment, or activation / deactivation of (multiple) light sources, can be controlled by transmitting control signals to the lighting equipment via a control unit or controller.

[0003] By connecting lamps, luminaires, or lighting equipment to a controller, new functionalities can be facilitated or enabled. For example, the examples mentioned above could be beneficial in the field of decorative luminaires or lighting, where the color or intensity of the light source can be adjusted according to the user's wishes.

[0004] US2019 / 041013 discloses a lighting device comprising two or more independently controlled light sources operable within a structure having a floor surface and a ceiling surface. A first light source emits light with a predetermined correlated color temperature upwards toward the ceiling portion directly above the lighting device, unobstructed by the lighting device. A second light source emits light with a predetermined correlated color temperature downwards toward the floor surface. A controller independently adjusts the color temperature and intensity of the light sources according to a schedule. Summary of the Invention

[0005] Beyond the many inventive approaches to the controllability of light sources in decorative lighting, a new functionality may lie in the field of luminaires or light engines that desire "up and down lighting" capabilities. The object of this invention is to provide a light-emitting device whose constituent light source has a controllable and adjustable color temperature and luminous flux.

[0006] According to a first aspect of the invention, this and other objectives are achieved by a light-emitting device configured to tunably emit light with a total color temperature (CT). tot The light-emitting device includes: a carrier having a first main surface and a second main surface opposite to the first main surface; and a first light source disposed on the first main surface of the carrier and arranged to emit first light having a first color temperature (CT1), the first color temperature being lower than that of a first low color temperature (CT1). low ) to the first high color temperature (CT1) high The first color temperature range is tunably adjustable; the second light source, which is arranged on the second main surface of the carrier, is arranged to emit second light having a second color temperature (CT2), the second color temperature being adjustable from the second higher color temperature (CT2).high ) to the second low temperature (CT2) low The second color temperature range is tunably adjustable; the controller is configured to independently control the first and second light sources so as to tunably adjust the first and second color temperatures from a first state to a second state according to a pre-selected scheme by adjusting the first color temperature from CT1 of the first state. low CT1 added to the second state high And the second color temperature from the first state CT2 high CT2 reduced to the second state low This ensures that the total color temperature of the light-emitting device remains constant in both the first and second states.

[0007] In total color temperature, this should be understood as the overall color temperature of the lighting equipment. This would be the average color temperature of the first and second light sources, while taking into account the luminous flux of these light sources.

[0008] It should be noted that, in the context of this invention, the same color temperature can be defined as a difference of less than 300K between the first and second color temperatures, more preferably less than 250K, and most preferably less than 200K.

[0009] One advantage of maintaining a constant overall color temperature is its decorative effect. More specifically, when looking directly at a light source, a user can distinguish the different color temperatures of two light sources; for example, the first source might emit a cooler white light, while the second might emit a warmer white light. Meanwhile, the color temperature will remain constant when viewed over a wider area of ​​the overall ambient lighting surrounding the light source.

[0010] According to the first main embodiment, the luminous flux of the first and second light sources is equal.

[0011] It should be noted that, for simplicity, when the luminous flux of the first and second light sources is equal, the total color temperature can be defined as the average of the first and second color temperatures under any given condition. In the context of this invention, equal luminous flux can be defined as the difference in luminous flux between the first and second light sources preferably being less than 50 lumens, more preferably less than 45 lumens, and most preferably less than 40 lumens.

[0012] Having the same luminous flux means that, in order to maintain the total color temperature in the second state equal to that in the first state, the color temperature changes of the first and second color temperatures should be equal, regardless of their starting points in the first state (CT1). low and CT2 high ), or their endpoint in the second state (CT1) high and CT2 low These embodiments can lead to a symmetrical depotential effect in the light-emitting device.

[0013] In either of the two specific cases of this first embodiment, the first and second color temperatures are equal—and equal to the total color temperature—in either the first or second state. Therefore, in other words, the first and second color temperatures will either start equal and then diverge, or start different and then converge, while the total color temperature is maintained.

[0014] In another specific case of the first main embodiment, the first color temperature increases from A to B, while the second color temperature decreases from B to A; in other words, CT1. low =CT2 low , while CT1 high =CT2 high .

[0015] During the transition between the first and second states, the equal luminous flux of the first and second light sources can remain constant, or it can differ slightly during the transition, depending on the desired visual effect.

[0016] According to the second main embodiment, the luminous flux of the first and second light sources is different in the first and second states. The different luminous flux of the first and second light sources may remain constant during the transition between the first and second states, or may differ slightly during the transition, depending on the desired visual effect.

[0017] The result of this embodiment is that, in the first state, the total color temperature will be closer to that of the light source with higher luminous flux. In order to maintain the same total color temperature in the second state, the color temperature of the light source with lower luminous flux needs to vary more, that is, the color temperature range of the light source should be greater than that of the other light source.

[0018] According to the third main embodiment, the controller is further configured to separately control the first luminous flux (F1) of the first light source and the second luminous flux (F2) of the second light source.

[0019] More specifically, the first light source in CT1 low The first luminous flux (F1) is located at this point. A ), in CT1 high The second luminous flux (F1) is located at this point. B The second light source is in CT2. high The first luminous flux (F2) is located at this point. A ), in CT2 low It has a second luminous flux (F2) B ).

[0020] By simultaneously controlling the color temperature and luminous flux of the first and second light sources, the controller can have various pre-selected control schemes to achieve the technical effect of keeping the total color temperature of the light-emitting device constant while providing visual effects.

[0021] As an example, in the first state, when the first and second color temperatures are equal (CT1) low =CT2 high As long as the luminous flux of the first and second light sources changes accordingly, the color temperature of the first and second light sources can change to different degrees.

[0022] For example, if the increase in color temperature of the first light source is greater than the decrease in color temperature of the second light source (|CT1) low -CT1 high |>|CT2 low -CT2 high To compensate for the increase in cold light emitted from the first light source, the luminous flux of the second light source may need to be increased (F2). A <F2 B ), and / or the luminous flux of the first light source decreases (F1) A F1 B Conversely: if (|CT1) low -CT1 high |<|CT2 low -CT2 high |), then (F1) A <F1 B ) and / or (F2) A >F2 B ).

[0023] It should be noted that the increase or decrease in luminous flux of the first and second light sources can be equal, or in addition, the luminous flux of the first and second light sources can be equal in the first or second state (F1). A =F2 A , or F1 B =F2 B ).

[0024] Alternatively, the difference in luminous flux of the first light source from the first state to the second state is not equal to the difference in luminous flux of the second light source from the first state to the second state |F1 A -F1 B |≠|F2 A -F2 B The increase or decrease in luminous flux of the first and second light sources is not necessarily equal, in order to achieve the desired effect of keeping the total color temperature of the light-emitting device constant.

[0025] According to one embodiment, the light-emitting device includes: at least one light-emitting diode (LED) filament, including an elongated carrier having a first main surface and a second main surface opposite to the first main surface, a first light source being a plurality of first LEDs mounted on the first main surface of the elongated carrier and arranged to emit first light having a first color temperature (CT1), and a second light source being a plurality of second LEDs mounted on the second main surface of the elongated carrier and arranged to emit second light having a second color temperature (CT2).

[0026] The advantage of this embodiment is that the light-emitting device, such as a filament lamp, can be tuned from a first symmetrical state to a second state, in which light with different color temperatures or colors can be emitted from both sides, while maintaining the total color temperature of the light emitted by the light-emitting device to the environment.

[0027] According to one embodiment of the LED filament, a plurality of first LEDs include two or more subsets of LEDs, each subset emitting a different color point and being individually controllable by a controller, and a plurality of second LEDs include two or more subsets of LEDs, each subset emitting a different color point and being individually controllable by a controller.

[0028] According to this embodiment, in order to achieve a certain white color temperature of the first light source (CT1), the intensity and / or activity of two or more subsets of LEDs with different color points can be controlled relative to each other. A similar approach can be adapted to achieve a certain color temperature of the light emitted by the second light source (CT2).

[0029] According to one embodiment, two or more subsets of LEDs, comprising a plurality of first LEDs or a plurality of second LEDs, include a first subset of LEDs arranged to emit cool white light and a second subset of LEDs arranged to emit warm white light. In this case, the intensity and / or activity of the subsets having warm white light and cool white light can be controlled relative to each other to obtain a desired color temperature of the first or second light source.

[0030] Additionally or alternatively, for either side of the LED filament, a subset of LEDs from the first or second light source can be controlled to obtain a certain total color point from that particular light source.

[0031] In one embodiment of the LED filament, two or more subsets of the plurality of first LEDs or the plurality of second LEDs include red, green, and blue subsets, each subset comprising red, green, and blue LEDs respectively. Therefore, these subsets can emit red, green, and blue light respectively.

[0032] According to a second aspect, a lamp includes a light-emitting device, a light-transmitting cover that at least partially covers the light-emitting device, and a connector for electrically and mechanically connecting the lamp to a socket.

[0033] The connector can be an electrical connector, such as, but not limited to, threaded Edison connectors, such as E26 or E27.

[0034] It should be noted that the present invention relates to all possible combinations of features described in the claims. Attached Figure Description

[0035] The invention will now be described more fully with reference to the accompanying drawings, in which presently preferred embodiments of the invention are shown. However, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided to be thorough and complete, and to fully convey the scope of the invention to those skilled in the art.

[0036] Figure 1 A light-emitting device according to the first aspect of the present invention is demonstrated.

[0037] Figure 2 An example of a pre-selected control scheme was demonstrated.

[0038] Figure 3 An example of a pre-selected control scheme was demonstrated.

[0039] Figure 4 An example of a pre-selected control scheme was demonstrated.

[0040] Figure 5 An example of a pre-selected control scheme was demonstrated.

[0041] Figure 6 An embodiment of the light-emitting device was demonstrated.

[0042] Figure 7 The light temperature / spectrum of the light-emitting device in the first state is demonstrated on the chromaticity diagram.

[0043] Figure 8 The light temperature / spectrum of the luminescent device in the second state on the chromaticity diagram is demonstrated.

[0044] Figure 9 The light temperature / spectrum of the luminescent device in the second state on the chromaticity diagram is demonstrated.

[0045] As illustrated in the accompanying drawings, the dimensions of the layers and regions are exaggerated for illustrative purposes, and therefore these dimensions are provided to illustrate the general structure of embodiments of the invention. Similar reference numerals throughout the text refer to similar elements. Detailed Implementation

[0046] Figure 1A light-emitting device 1 according to a first aspect of the invention is schematically demonstrated. A first light source 10 is arranged on a first main surface 42 of a carrier 40, while a second light-emitting device 20 is arranged on a second main surface 44 of the carrier 40 opposite to the first main surface 42. The first light-emitting device is arranged to emit a first light L1 having a first color temperature CT1 substantially in a first direction D1, wherein the first color temperature CT1 is a first low color temperature CT1. low And the first high color temperature CT1 high The two are tunable, and the second light-emitting device 20 is arranged to emit a second light L2 with a second color temperature CT2 in a second direction D2 that is substantially opposite to the first direction k. The second color temperature CT2 is a second high color temperature CT2. high Second Low Color Temperature CT2 low The values ​​are tunable. The total color temperature emitted by light-emitting device 1 is CT. tot The first light source 10 and the second light source 20 are connected to the controller 50 via an electrical connection cable 30.

[0047] exist Figure 2 The graph illustrates an embodiment of the pre-selected scheme for controller 50. The x-axis represents time t, marked with the first state t1 and the second state t2, while the y-axis represents color temperature (CT). It should be noted that... Figure 2 and Figure 3 In this embodiment, the luminous fluxes F1 and F2 of the first light source 10 and the second light source 20 are assumed to be equal to each other and remain unchanged from the first state t1 to the second state t2. This is achieved by adjusting the first color temperature from CT1 in the first state t1. low CT1 added to the second state t1 high (L1), and by changing the second color temperature from CT2 under the first state t1 high CT2 reduced to the second state t2 low (L2) The controller 50 independently controls the first light source 10 and the second light source 20 to tunably adjust the first and second color temperatures according to a pre-selected scheme, so that the total color temperature of the light-emitting device remains constant in the first and second states. As observed, the first and second color temperatures are equal, and therefore equal to the total color temperature (CT1) in the first state t1. low =CT2 high =CT tot In order to maintain CT in the second state t2. tot The total color temperature, the range of the first color temperature r1, must be equal to the range of the second color temperature r2. In other words: r1 = |CT1| low -CT1 high |=|CT2 low -CT2 high |=r2.

[0048] exist Figure 3 The figure provided illustrates an embodiment of the pre-selected control scheme, where the first color temperature CT1 is shown in the first state t1. low Second color temperature CT2 high They are not equal. In order for controller 50 to maintain the total color temperature of the light-emitting device 1 at CT... tot In the second state t2, the first color temperature needs to be decreased by L1 and the second color temperature increased by L2 so that the first color temperature in the second state t2 is equal to the second color temperature in the first state (CT1). high =CT2 high The second color temperature in the second state t2 is equal to the first color temperature (CT2) in the first state t1. low =CT1 low Therefore, the ranges of the first and second color temperatures will be equal, r1 = r2.

[0049] In the following embodiments of the pre-selected control scheme ( Figure 4 and Figure 5 The luminous flux of the first light source 10 and the second light source 20 in the first state t1 (F1 and F2 respectively) A and F2 A ) is not equal to the luminous flux in the second state t2 (respectively F1) B and F2 B ): F1 A ≠F1 B And F2 A ≠F2 B It is also worth noting that while the y-axis on the left-hand side continues to represent color temperature (CT), the y-axis on the right-hand side shows luminous flux (F).

[0050] exist Figure 4 In the embodiment, the first and second color temperatures in the first state t1 are equal, and are equal to the total color temperature of the light-emitting device 1: CT1 low =CT2 high =CT tot The luminous flux of the first light source 10 and the second light source 20 is equal at the first state t1: F1 A =F2 A The controller 50 tunes to a first color temperature along L1 with a range of r1, and tunes to a second color temperature along L2 with a range of r2, such that the ranges of the two color temperatures are not equal, with the first range being larger than the second: r1 = |CT1| low -CT1 high |>|CT2 low -CT2 high |=r2.

[0051] In such embodiments of a preselected control scheme where the tunable ranges of the first light source 10 and the second light source 20 are not equal, in order to maintain the total color temperature of the light-emitting device 1 at CT in the second state t2... tot The luminous flux of the first light source 10 and the second light source 20 needs to be changed in corresponding opposite directions. Figure 4 In this embodiment, this means that the luminous flux of the first light source 10 decreases, while the luminous flux of the second light source 20 increases. The changes in the luminous flux of the first light source 10 and the second light source 20 are depicted by dashed lines L1′ and L2′, respectively. It can be observed from this figure that F1 A F1 B And F2 A <F2 B In short, the luminous flux of the light source with the more drastic color temperature change (the first light source 10 in this embodiment) will decrease from the first state t1 to the second state t2. The other light source with a smaller color temperature change (the second light source 20 in this embodiment) can maintain the same luminous flux (F2) as the first state t1 in the second state t2. A =F2 B ), or like Figure 4 In the case of the embodiment, its luminous flux can be increased.

[0052] exist Figure 5 In the embodiment, the first and second color temperatures are not equal in the first state t1 (CT1) low ≠CT2 high Furthermore, in the first state t1, the luminous flux of the first light source 10 and the second light source 20 are not equal: F1 A ≠F2 A Note that the total color temperature (CT) of the luminescent device 1 is... tot This will be the value corresponding to the intensity of the luminous flux from each different color temperature. This is to ensure the controller maintains the same total color temperature CT in the second state t2. tot The luminous flux of the first light source 10 and the second light source 20 needs to be adjusted according to the changes in the first and second color temperatures.

[0053] Figure 6An embodiment of an LED filament 100 of a light-emitting device 1 is shown. In the context of this invention, the LED filament 100 of the light-emitting device 1 can be described as follows: A plurality of first LEDs 110 are arranged on a first main surface 122 of an elongated carrier 120. Note that in this text, the terms "carrier" and "substrate" are used interchangeably and, unless otherwise stated, have the same meaning. The LEDs 110 are covered by an encapsulation 152 that at least partially covers the first main surface 122 of the elongated carrier 120. These LEDs 110, together with their encapsulations 152, correspond to a first light source 130 of the light-emitting device 1. A plurality of second LEDs 110, covered by an encapsulation 154, are arranged on a second main surface 124 of the elongated carrier 120 opposite to the first main surface 122. These LEDs 110, together with their encapsulations 154, correspond to a second light source 140 of the light-emitting device 1. The first light source 130 and the second light source 140 are connected to a controller 50 via an electrical connector 30. The controller tunes the first and second color temperatures of the first light source 130 and the second light source 140 from the first low color temperature in the first state t1 to the first high color temperature in the second state t2, and from the second high color temperature in the first state t1 to the second low color temperature in the second state t2, respectively.

[0054] Preferably, the LED filament 100 has a length G and a width W, where G > 5W. The LED filament 100 can be arranged in a manner similar to... Figure 6 The linear configuration can also be arranged in a non-linear configuration, such as, for example, a curved configuration, a 2D / 3D spiral, or a helix.

[0055] The linear array of LEDs 110 can be arranged in the longitudinal direction of the elongated carrier 120. The linear array is preferably an NxM matrix of LEDs 110, where N = 1 (or 2), M is at least 10, more preferably at least 15, and most preferably at least 20, such as at least 30 or 36 LEDs 110.

[0056] The carrier 120 can be rigid (e.g., made of polymer, glass, quartz, metal or sapphire) or flexible (e.g. made of polymer, such as film or foil).

[0057] The rigid material carrier can provide better cooling for the LED filament 100, which means that the heat generated by the LED 110 can be dissipated by the rigid substrate 120.

[0058] Because of its flexibility, the carrier 120 of the flexible material can provide shape freedom for designing the aesthetics of the LED filament 100.

[0059] It should be noted that thin, flexible materials often have poorer thermal management compared to rigid materials. However, on the other hand, using a rigid material as the substrate 120 may limit the shape design of the LED filament 100.

[0060] The carrier 120 may be light-reflective. In this embodiment, the light emitted by the LED 110 is reflected from the surfaces 122 and 124 of the carrier 120 on which the LED 110 is disposed, thereby hindering the propagation of light on the filament carrier 120.

[0061] Furthermore, LED 110 can be arranged to emit LED light of, for example, different colors or spectra. Packages 152 and 154 may include a light-emitting material configured to at least partially convert the LED light into converted white light. The light-emitting material may be a phosphor, such as an inorganic phosphor, blue and / or green-yellow and / or orange-red phosphor, and / or quantum dots or rods.

[0062] Alternatively or additionally, packages 152, 154 may include light-scattering materials.

[0063] Each LED 110 in the LED filament 100 can emit white light. The LED can emit either cool white light or warm white light. The LED can be a blue or ultraviolet LED covered by packages 152, 154, therefore the packages 152, 154 include luminescent materials, such as phosphor particles. The luminescent material provides wavelength conversion for the light from the LED 110, and the light emitted from this portion will be white light composed of a mixture of blue / ultraviolet light and the wavelength-converted light. This white light can have a color temperature at the black body line.

[0064] Alternatively or additionally, the LED filament 100 may include red (R) and blue (B) LEDs covered by packages 152, 154, such that packages 152, 154 include light-emitting material.

[0065] Alternatively or simultaneously, the LED filament 100 may include groups of red (R), green (G), and blue (B) LEDs 110, wherein the light emitted from each RGB LED 110 is combined to produce white light with a cool or warm color temperature. The red, green, and blue LEDs 110 in each group may be arranged in groups or one after another in the longitudinal direction of the LED filament 100.

[0066] The white light will have an adjustable color temperature. This can be achieved by including at least two different types of LEDs 110 (e.g., red and blue LEDs). By controlling the relative intensity of each type of LED 110, the color temperature of the emitted light can be controlled.

[0067] Additionally or alternatively, the light emitted by the LED filament 100 can be tunable to any color of the spectrum. This can be achieved by individually controlling the activity and / or intensity of each RGB LED 110.

[0068] Besides simply changing the total color temperature and / or luminous flux of the first light source 10, 130 and the second light source 20, 140 of the light-emitting device 1, another method to maintain a constant total color temperature from the first state t1 to the second state t2 is to tamper with the color of the light emitted from the light source.

[0069] According to an alternative embodiment, the light emitted by the first light source 10, 130 and the second light source 20, 140 in the first state t1 and / or the second state t2 may not be white light of different temperatures, but rather light of a color other than white, such as, but not limited to, red or green. In this case, the sum of the non-white light emitted by the first light source 10, 130 and the second light source 20, 140 may fall on a blackbody trajectory. This may mean that even though the light emitted from each light source may be a different color, the total light emitted from the light-emitting device may be white, having a certain color temperature d1 defined by the color temperature of the light-emitting device 1 in the first state t1.

[0070] Figures 7 to 9 A chromaticity diagram was demonstrated, on which the blackbody locus is depicted by a full line, while the spectral locus is depicted by a dashed line. The total color temperature (CT) of the luminescent device 1 is shown. tot It will be on the blackbody trajectory, depending on the warmth or coolness of the total white light emitted from the light-emitting device 1, and will be indicated by point X.

[0071] Figure 7 The light temperature / spectrum of the light-emitting device 1 in a first state t1 is demonstrated according to one embodiment. According to this particular embodiment, the total color temperature is approximately 3500K. Based on this figure, it can be understood that the first and second color temperatures also fall at point X in the first state.

[0072] Figure 8 The temperature / spectrum of the light-emitting device 1 in the second state t2 is demonstrated. It can be observed that the first color temperature increases from point X along the blackbody trajectory to point Z, so point Z remains on the blackbody trajectory. This means that the light emitted from the first light source 10, 130 is still white, only cooler in the second state t2. Similarly, the second color temperature decreases from point X along the blackbody trajectory to point Y, so point Y also remains on the blackbody trajectory. This means that the light emitted from the second light source 20, 140 is still white, only warmer in the second state t2. The total color temperature is denoted by X, and as observed, the temperature remains... Figure 7 At the same point (first state t1).

[0073] Figure 9Another embodiment of the pre-selected control scheme according to controller 50 is demonstrated, showing the light temperature / spectrum of the light-emitting device 1 in the second state t2. In this embodiment, the light from the first light sources 10 and 130 is tuned away from the blackbody trajectory and directed towards a greenish color in the spectrum. The spectra of the first light-emitting devices 10 and 130 are shown as point m. Similarly, the spectra of the second light sources 20 and 140 are tuned away from the blackbody trajectory and directed towards a reddish color. This is marked by point n. Note that in order to maintain the total color temperature of the light-emitting device 1 at CT in the second state t2... tot At point (X), the color tuning of the first light source 10, 130 and the second light source 20, 140 needs to be performed in opposite directions within the spectral trajectory.

[0074] Those skilled in the art will recognize that the invention is by no means limited to the preferred embodiments described above. Rather, many modifications and variations are possible within the scope of the appended claims. For example, in one embodiment, the pre-selected scheme is such that the first and second luminous fluxes do not increase or decrease along the linear path demonstrated in all embodiments of the specification, but rather increase or decrease along a sine function with a constant amplitude, or alternatively, the amplitude is variable.

[0075] Furthermore, by studying the accompanying drawings, the disclosure, and the appended claims, those skilled in the art can understand and implement variations of the disclosed embodiments. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude multiple. The fact that certain measures are recited merely in mutually different dependent claims does not indicate that a combination of these measures cannot be used advantageously.

Claims

1. A light-emitting device configured to tunably emit light with a total color temperature (CT). tot The light-emitting device includes: -At least one light-emitting diode (LED) filament, comprising an elongate carrier having a first major surface and a second major surface opposite the first major surface; - A first light source, comprising a plurality of first LEDs arranged on the first main surface of the carrier and configured to emit first light having a first color temperature (CT1), the first color temperature being lower than a first low color temperature (CT1). low ) to the first high color temperature (CT1) high The first color temperature range is tunable and adjustable, and the range of the first color temperature is r1 = |CT1|. low -CT1 high | and has a first luminous flux F1, - A second light source, comprising a plurality of second LEDs arranged on the second main surface of the carrier and configured to emit second light having a second color temperature (CT2), the second color temperature being higher than a second high color temperature (CT2). high ) to the second lowest color temperature (CT2) low The second color temperature range is tunable, and the range of the second color temperature is r2 = |CT2|. low -CT2 high | and has a second luminous flux F2, - A controller configured to independently control the first light source and the second light source, so as to tunably adjust the first color temperature and the second color temperature from a first state to a second state according to a pre-selected scheme by means of the following operation: the operation being to adjust the first color temperature from the CT1 of the first state... low CT1 added to the second state high And the second color temperature from the first state CT2 high CT2 reduced to the second state low , The controller is further configured to control the first luminous flux F1 and the second luminous flux F2 such that if r1 < r2, the change in F1 is greater than the change in F2, and vice versa, so that the total color temperature of the lighting device remains constant in the first state and the second state.

2. The lighting device according to claim 1, wherein the difference between the first color temperature and the second color temperature is less than 300 K.

3. The lighting device according to claim 1, wherein the luminous fluxes of the first light source and the second light source are equal in the first state and the second state.

4. The lighting device according to claim 3, wherein the luminous fluxes of the first light source and the second light source remain constant during the transition from the first state to the second state.

5. The lighting device according to claim 4, wherein the first color temperature and the second color temperature are equal in the first state or in the second state.

6. The lighting device according to claim 4, wherein the first color temperature in the first state is equal to the second color temperature in the second state, and the second color temperature in the first state is equal to the first color temperature in the second state.

7. The lighting device according to claim 1, wherein the luminous fluxes of the first light source and the second light source are different in the first state and the second state.

8. The lighting device according to claim 7, wherein the luminous fluxes of the first light source and the second light source remain constant during the transition from the first state to the second state.

9. The lighting device according to claim 1, wherein the difference in luminous flux of the first light source from the first state to the second state is different from the difference in luminous flux of the second light source from the first state to the second state.

10. The light-emitting device according to any one of claims 1-9, wherein the change in the first color temperature is different from the change in the second color temperature (|CT1) low -CT1 high |≠|CT2 low -CT2 high |).

11. The lighting device according to any one of claims 1 to 9, wherein the plurality of first LEDs comprises two or more LED subsets, each subset emitting a different color point and being individually controllable by the controller, and the plurality of second LEDs comprises two or more LED subsets, each subset emitting a different color point and being individually controllable by the controller.

12. The lighting device according to any one of claims 1 to 9, wherein two or more LED subsets of the plurality of first LEDs or the plurality of second LEDs comprise a first LED subset arranged to emit white light having a first color temperature and a second LED subset arranged to emit white light having a second color temperature, wherein the first color temperature is higher than the second color temperature.

13. The lighting device according to any one of claims 1 to 9, wherein two or more LED subsets of the plurality of first LEDs or the plurality of second LEDs comprise a red subset, a green subset, and a blue subset, each subset comprising red LEDs, green LEDs, and blue LEDs, respectively.

14. A lamp, comprising: The light-emitting device according to any one of claims 1 to 13; A light-transmitting cover that at least partially covers the light-emitting device; as well as A connector for electrically and mechanically connecting the lamp to the socket.

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