Lighting device

Abstract

A light emitting device configured to emit light having a total color temperature (CTtot), the light emitting device comprising at least one first light emitting diode (LED) filament and at least one second LED filament, wherein each of the at least one first LED filament and the at least one second LED filament comprises an elongated carrier, and an array of light emitting diodes mounted on the substrate; and a controller for individually controlling the at least first LED filament and the at least one second LED filament, wherein the at least one first LED filament is arranged to emit light of a first color temperature (CT1), the first color temperature being controllable within a first color temperature range from CT1 low to CT1 high , wherein the at least one second LED filament is arranged to emit light of a second color temperature (CT2), the second color temperature being controllable within a second color temperature range from CT2 low to CT2 high , and wherein the controller is configured to control the total color temperature (CTtot) from a first total color temperature (CTtot,1) to a second total color temperature (CTtot,2) by controlling the first color temperature and the second color temperature according to a preselected control scheme, such that a difference (ACT) between the first color temperature and the second color temperature is not constant during the change of CTtot.

Description

Technical Field

[0001] This invention relates to LED filaments, specifically linear arrays of LEDs arranged on a carrier substrate, used, for example, in modified light bulbs. More specifically, this invention relates to color-controllable LED filaments. Background Technology

[0002] Incandescent bulbs are being rapidly replaced by LED-based lighting solutions. However, users can understand and expect to have modified lamps that retain the appearance of incandescent bulbs. This can be achieved by simply utilizing the infrastructure used to produce glass-based incandescent bulbs and replacing the filament with LEDs that emit white light. One such concept is based on LED filaments placed within such bulbs. These lamps have a very appealing appearance, as they are highly decorative.

[0003] As is well known in the lighting industry, the color temperature of a dimmable incandescent bulb changes as the bulb dims. However, the color temperature of an LED typically becomes cooler when the drive current decreases. Therefore, simply dimming an LED light source in the same way as an incandescent bulb produces an unnatural result in terms of color temperature change compared to an incandescent bulb. Therefore, there is a need for a color-temperature-controlled LED filament that mimics the color temperature change of a modified incandescent bulb when dimmed, providing a comfortable aesthetic.

[0004] Typically, in color temperature variable lamps with adjustable LED filament color temperature, all filaments have the same appearance.

[0005] US20180328543 A1 proposes a solution to this problem as a lamp comprising a light-transmitting housing for emitting emitted light and a base connected to the housing. At least one first LED filament and at least one second LED filament are located within the housing. The first LED filament emits light with a first correlated color temperature, and the second LED filament emits light with a second correlated color temperature; they are combined to produce emitted light. A controller is used to change the correlated color temperature of the emitted light when the lamp is dimmed. In this document, two different types of filaments with two different color points are used to dim the lamp and simultaneously change its color, such that the operation of the lamp can mimic the color changes associated with a dimmable incandescent bulb. Dimming used here means a reduction in the luminous flux of the light emitted from the lamp. However, document US20180328543A1 fails to address the loss of the pleasing appearance of the flame filament at higher color temperatures.

[0006] In WO 19197394A1, a light-emitting diode (LED) filament lamp includes at least one filament extending along a longitudinal axis A in a length L, wherein the LED filament includes an array of a plurality of LEDs extending along the longitudinal axis, and an encapsulation at least partially surrounding the plurality of LEDs, wherein the encapsulation includes a light-emitting material, and wherein at least one of the thickness TL of the encapsulation along a transverse axis B perpendicular to the longitudinal axis and the concentration CL of the light-emitting material in the encapsulation varies over at least a portion of the length L of the at least one filament along the longitudinal axis, thereby causing the color temperature CTL of the light emitted from the at least one LED filament to vary at least a portion of the length of the at least one LED filament.

[0007] Therefore, alternative solutions that can solve the above problems are needed. Summary of the Invention

[0008] One object of the present invention is to overcome this problem and to provide an LED filament lighting device that, while maintaining the pleasing appearance of the lighting device, achieves a more durable flame-like appearance similar to that of an incandescent lamp.

[0009] This and other objectives are achieved by providing a lighting device having the features of independent claim 1. Preferred embodiments are defined in the dependent claims.

[0010] According to a first aspect of the invention, a light-emitting device configured to emit light having a total color temperature is provided, the light-emitting device comprising at least one first light-emitting diode (LED) filament and at least one second LED filament, wherein each of the at least one first LED filament and the at least one second LED filament comprises an elongated substrate and an array of LEDs mounted on the substrate; and a controller for individually controlling the at least one first LED filament and the at least one second LED filament. The at least one first LED filament is arranged to emit light having a first color temperature, the first color temperature being determined from CT1. low To CT1 high The first color temperature is controllable, wherein the at least one second LED filament is arranged to emit light having a second color temperature, which is within the range of CT2. low To CT2 high The second color temperature is controllable, and the controller is configured to control the total color temperature (CTtot) from the first total color temperature (CTtot,1) to the second total color temperature (CTtot,2) by controlling the first color temperature and the second color temperature according to a pre-selected control scheme, such that the difference (ΔCT) between the first color temperature and the second color temperature is not constant during the change of CTtot from CTtot,1 to CTtot,2' (which is also referred to as the change of total color temperature (CTtot)).

[0011] "Color temperature control" here refers to the ability to control the wavelength of emitted light, which can include wavelengths in the color spectrum as well as white light. Each LED filament can be configured to emit a single (uniform) color or several separate (non-uniform) colors.

[0012] In this invention, a non-constant ΔCT is achieved by maintaining a second color temperature lower than the first color temperature for most of the time. Specifically, at the endpoints, CTtot,1 and CTtot,2, the second color temperature can be equal to the first color temperature. By maintaining the second color temperature below or at most equal to the first color temperature, the second filament can maintain a flame-like appearance consistently or at least for a longer duration during dimming of the lighting device. Therefore, the controller can effectively control the total color temperature emitted by the LED filament lighting device while providing a more desired (e.g., flame-like) appearance.

[0013] Another advantage of the present invention is that the color temperature of the light emitted from each of the first and second filaments of the lighting device can be controlled according to one or more pre-selected control schemes, thereby controlling the color of the light emitted from the LED filament lighting device in a universal manner.

[0014] Note that CT1 low and CT2 low This corresponds to the starting point of the control scheme with an initial difference ΔCTstart, and their sum is CTtot,1. Therefore, CTtot,1 and ΔCTstart correspond to the same time point. Following the same logic, CT1 high and CT2 high This corresponds to the end point of the control scheme with the final difference ΔCTend, and the sum is CTtot,2. Therefore, CTtot,2 and ΔCTend correspond to the same time point.

[0015] In one embodiment, the total number of first LED filaments can be greater than the total number of second LED filaments. Similar to the embodiment described above, this embodiment benefits from achieving a high CTtot of the lighting device more easily and at a lower intensity.

[0016] Alternatively, in another embodiment, the total number of first LED filaments can be less than the total number of second LED filaments. The advantage of this embodiment is that it can provide a more "retro" look for LED filament lighting devices.

[0017] In another embodiment, the same number of first and second LED filaments are present, which can result in a more uniform appearance.

[0018] According to some embodiments, CT1 low and CT2 lowThe difference between them, i.e., ΔCTstart, is preferably less than 500K, more preferably less than 300K, and most preferably less than 100K.

[0019] According to some embodiments, CT1 high and CT2 high The difference between them, i.e., ΔCTend, is preferably less than 500K, more preferably less than 300K, and most preferably less than 100K.

[0020] According to one embodiment, CT1 low and CT2 low Preferably, the K value is 1800-2500K, more preferably 2000-2400K, and most preferably 2100-2300K.

[0021] It is generally known that a typical Edison-type incandescent bulb has a full illumination temperature of approximately 2700K, and dims to a warmer 2200K at approximately 10% or even lower of full illumination. A candelabra-type incandescent bulb can be dimmed to a warmer 1800K at approximately 10% illumination. Therefore, the aforementioned range of "low" color temperatures between the first and second filaments ensures the warm, flame-like appearance of LED filament lighting fixtures.

[0022] According to one embodiment, CT1 high and CT2 high The preferred K value is 2700-4500K, the more preferred K value is 2900-4000K, and the most preferred K value is 3000-3500K.

[0023] The first color temperature range can overlap with the second color temperature range. This offers the advantage of better aesthetics because both types of filaments have more uniform color temperatures. Otherwise, the two different types of filaments might become visually distinguishable due to their significantly different color temperatures. Alternatively, the first and second color temperature ranges can be the same. In this case, the control paths for the first and second color temperatures can be different, but the starting point (CT1) remains the same. low and CT2 low ) and their endpoints (CT1) high and CT2 high They can land together.

[0024] According to some embodiments, it can be done on CT. tot,1 Location, CT1 low Equal to CT2 low This requires controlling the first and second LED filaments to ensure their initial color temperatures are equal. Alternatively, or alternatively, this can be achieved in a CT... tot,2 Location, CT1 high Equal to CT2 highThis requires controlling the first and second LED filaments to ensure that their final color temperatures are equal.

[0025] The color temperature of the first and second LED filaments can be controlled in various ways. For example, the controller can be configured to change the first and second color temperatures by simultaneously controlling all LEDs in each filament. In other words, all LEDs in the filament are controlled to emit light of the same color temperature. This can result in uniform control of all LEDs on the filament. Alternatively, the controller can be configured to change the first and second color temperatures by individually controlling the LEDs in each filament. In other words, a subset of the LEDs in the filament can emit light of one color temperature, while another subset emits light of a different color temperature. This can result in LED-specific control.

[0026] In one embodiment, to increase the overall color temperature, a pre-selected control scheme includes: in a first stage, increasing the difference between the first and second color temperatures, ΔCT, by increasing the first color temperature while maintaining, decreasing, or slightly increasing the second color temperature; and in a subsequent second stage, decreasing the difference between the first and second color temperatures, ΔCT, by maintaining, decreasing, or slightly increasing the first color temperature while increasing the second color temperature. By increasing the first color temperature alone, the flame-like appearance of the lighting device can be maintained for a longer duration, similar to what is expected from a typical incandescent lamp when dimmed. If the user desires further increased intensity, the color temperature of the second filament can be increased, thereby increasing the overall color temperature of the LED filament lighting device, mimicking the behavior of incandescent lamps as their intensity increases.

[0027] For example, the color temperature of the first filament can be increased from 2000K to 2700K, while the second filament remains at 2000K, and then the second color temperature is increased to 2700K.

[0028] This increases the overall color temperature of the lighting fixture while maintaining its flame-like appearance during transitions.

[0029] The second stage can preferably be started when the first color temperature has been increased by at least 400K, more preferably by at least 500K, and most preferably by at least 600K.

[0030] According to one embodiment, the pre-selected control scheme includes controlling the first color temperature independently of the second color temperature.

[0031] In this configuration, one type of filament (first or second) can be completely switched on or off, regardless of whether the other type is on or off. This provides the possibility of tuning the overall color temperature of the LED filament lighting fixture within the color temperature range of the type of filament that is switched on. If the first filament is "on," the overall color temperature range will be higher, and therefore cooler. If the second filament is "on," the overall color temperature of the lighting fixture will be lower, and therefore warmer. In this case, depending on the color temperature range of the second filament, the lighting fixture can maintain a constant or at least longer flame-like appearance.

[0032] LED filaments and controllers can be included in a single device, resulting in a relatively compact color-controlled LED filament lighting device.

[0033] One or more such LED filament lighting devices can be incorporated into a modified bulb, which also includes a transmissive housing that at least partially surrounds the LED filament, and connectors for electrically and mechanically connecting the bulb to a receptacle.

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

[0035] This and other aspects of the invention will now be described in more detail with reference to the accompanying drawings, which illustrate embodiments of the invention.

[0036] Figure 1 The modified light bulb, which includes multiple LED filaments, is shown schematically.

[0037] Figure 2a A top view of such an LED filament according to at least one embodiment of the present invention is shown.

[0038] Figures 2b to 2d A side view of an LED filament according to different embodiments of the present invention is shown.

[0039] Figures 3a to 3c Different embodiments of an LED filament that emits tunable white light are shown.

[0040] Figure 4a A modified light bulb containing two LED filaments is shown, one with a first adjustable color temperature range and the other with a second adjustable color temperature range.

[0041] Figure 4b A top cross-sectional view of a modified bulb containing three LED filaments with a first color temperature adjustable range and three LED filaments with a second color temperature adjustable range is shown, giving the total number of six LED filaments.

[0042] Figure 5a , Figure 5b, Figure 5c and Figure 5d Illustrative drawings are shown of different pre-selected control schemes for increasing the total color temperature of the light-emitting device.

[0043] Figure 6 A flowchart describing the stages of a pre-selected control scheme is shown.

[0044] Figure 7 A diagram depicting the change in the difference between the first and second color temperatures (ΔCT) over time.

[0045] As shown in the figures, the dimensions of layers and regions have been exaggerated for illustrative purposes; therefore, these dimensions are provided to illustrate the general structure of embodiments of the invention. The same reference numerals consistently denote the same elements. Detailed Implementation

[0046] The invention will now be described more fully below with reference to the accompanying drawings, in which presently preferred embodiments of the invention are illustrated. 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 for thoroughness and completeness and to fully convey the scope of the invention to those skilled in the art.

[0047] Figure 1 A modified light bulb 10 is shown, comprising at least two LED filaments 100 housed within a housing 11. The LED filaments 100 (explained in more detail below) are connected to a controller 15 and an electrical (or mechanical) connector 12 via a connecting wire 13. Similar to a typical incandescent light bulb, this is shown... Figure 1 The middle part is the electrical connector 12 (here, a threaded Edison connector such as E26 or E27) for connecting the bulb 10 to an electrical socket (not shown). Note that in this document, "modified bulb" and "lamp" are used to refer to the same object and can be used interchangeably unless otherwise stated.

[0048] According to the present invention, the LED lighting device includes at least one first filament 100a ( Figure 4a ) and at least one second filament 100b, the first filament 100a being arranged to emit a first color temperature range (CT1) low -CT1 high The light within the second temperature range (CT2) is emitted by the second filament 100b. low -CT2 highThe first and second color temperature ranges can typically differ, with the first color temperature being higher than the second. However, it is important to note that the first color temperature range can overlap with the second color temperature range. This can provide the advantage of better aesthetics because the two types of filaments have a more uniform color temperature. Otherwise, the two different types of filaments might become distinguishable to the naked eye due to their very different color temperatures.

[0049] According to at least one implementation scheme, CT1 low and CT2 low Below 2500K, preferably below 2400K, and more preferably below 2300K, and / or wherein CT1 high and CT2 high Preferably above 2700K, more preferably above 2900K, and most preferably above 3500K.

[0050] Color temperature can also be within a certain range, such as CT1. low and CT2 low Preferably within the range of 1800-2500K, more preferably 2000-2400K, and most preferably 2100-2300K. At the higher end of the color temperature range, according to at least one embodiment, CT1 high and CT2 high Preferably, the K value is in the range of 2700-4500K, more preferably 2900-4000K, and most preferably 3000-3500K.

[0051] In the context of this invention, Figure 1 The LED filament 100 of the lighting device of the bulb 10 shown can be described as follows. Figure 2 illustrates this LED filament 100. The LED 110 is disposed on an elongated carrier 120, such as a substrate. Note that the terms "carrier" and "substrate" are used interchangeably herein and are intended to imply the same meaning unless otherwise stated. Preferably, the LED filament 100 has a length L and a width W, where L > 5W. The LED filament 100 can be arranged in a straight structure similar to that in Figure 2, or in a non-straight structure, such as a curved structure, a 2D / 3D spiral, or a coil.

[0052] LED filament 100 may include a package 150 that at least partially covers a plurality of LEDs 110. For example... Figure 2b and Figure 2d As shown in the side view schematic diagram, the encapsulation 150 may also at least partially cover at least one of the first main surface 130 and / or the second main surface 140. The encapsulation 150 may be a flexible polymer material, such as silicone.

[0053] The carrier 120 can be rigid (e.g., made of polymer, glass, quartz, metal or sapphire) or flexible (e.g. made of polymer or metal, such as film or foil).

[0054] The rigid material carrier 120 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 carrier 120.

[0055] Due to its flexibility, the carrier 120 of the flexible material can provide aesthetic shape freedom for designing the LED filament 100.

[0056] It should be noted that thin, flexible materials (such as foils) often have poorer thermal management compared to rigid materials. However, on the other hand, having a rigid material as a carrier 120 may limit the shape design of the LED filament 100.

[0057] The carrier 120 may include a first main surface 130 and an opposing second main surface 140. The LED 110 is disposed on at least one of these surfaces. Figure 2a and Figure 2c ).

[0058] The carrier 120 may be light-transmitting, such as translucent, or preferably light-transmitting. The light-transmitting substrate may be made of, for example, polymer, glass, quartz, etc.

[0059] The advantage of the light-transmitting substrate is that the light emitted from the LED 110 can propagate through the carrier 120, resulting in essentially omnidirectional light emission.

[0060] For the light-transmitting substrate, the encapsulation 150 can be disposed on both sides of the filament 100.

[0061] Alternatively, the carrier 120 may be reflective. In this embodiment, light emitted by the LED 110 is reflected from the surface of the substrate (130 and / or 140) on which the LED 110 is disposed, thereby preventing light from propagating to the filament carrier 120.

[0062] Furthermore, LED 110 can be arranged to emit LED light of, for example, different colors or spectra. Package 150 may include a light-emitting material configured to at least partially convert LED light into converted light. The light-emitting material may be a phosphor, such as an inorganic phosphor and / or quantum dots or rods.

[0063] Each LED 110 of the LED filament 100 can emit white light, such as Figure 1As shown. LED 110 can emit cool white light or warm white light. LED 110 can be a blue or UV LED covered by a package 150, such that the package 150 includes a light-emitting material, such as phosphor particles. The light-emitting material will provide wavelength conversion of the light from LED 110, and the light emitted from this portion will be white light composed of a mixture of blue / UV light and wavelength-converted light. The white light can have a color temperature at the blackbody line.

[0064] Alternatively, or simultaneously, such as Figure 3a and Figure 3b As shown, the LED filament 100 may include a group 210 of red (R) LEDs 211, green LEDs 212 (G), and blue LEDs 213 (B), wherein the light emitted from each of the RGB LEDs 211, 212, and 213 is combined to produce white light with a cool or warm color temperature. The red LEDs 211, green LEDs 212, and blue LEDs 213 in each group can be arranged as follows: Figure 3a Group 210 shown, or as Figure 3b As shown, the LED filaments 100 are arranged one after another in the longitudinal direction.

[0065] White light can have an adjustable color temperature. This can be achieved by including at least two different types of LEDs, such as a red LED 211 and a blue LED 213. The color temperature of the emitted light can be controlled by adjusting the relative intensity of each type of LED.

[0066] Figure 3c Another method for achieving color temperature adjustability is illustrated. In this embodiment, the LED filament 100 may comprise only one type of LED (e.g., blue LED 213) and alternatively have different areas covered by different types of packages 151, 152, 153, etc. Furthermore, the color temperature of the emitted light can be controlled by controlling the relative intensities of the LEDs 110 associated with the different packages 151, 152, 153, etc.

[0067] Color-controllable LEDs may include multiple LED groups 210, each LED group including a red LED 211, a green LED 212, and a blue LED 213.

[0068] LED filament 100 may include multiple sub-filaments.

[0069] Figure 4a An embodiment of a bulb 10 is shown, which includes two LED filaments 100a and 100b, each filament being arranged to emit light of a first color temperature and a second color temperature, respectively.

[0070] The total number of LED filaments—the sum of the first filament 100a and the second filament 100b in an LED filament lighting device—is preferably greater than two, more preferably greater than four, and most preferably greater than five, for example, six or eight.

[0071] In various embodiments, the total number of first LED filaments 100a may be greater than, less than or equal to the total number of second LED filaments 100b.

[0072] Figure 4b A top view of an embodiment of the present invention is shown, wherein the number of first LED filaments 100a is equal to the number of second LED filaments 100b, and is equal to three.

[0073] According to an aspect of the invention, in order to increase the total color temperature, the controller 15 of the light-emitting device operates with a pre-selected control scheme. Figure 5a , Figure 5b and 5c The steps of a pre-selected control scheme are schematically illustrated as a graph of color temperature relative to time, while Figure 6 A flowchart describing the stages of a pre-selected control scheme is shown.

[0074] As in Figure 5a As described, in the first stage, controller 15 increases the color temperature of filament 100a from a to b, while maintaining the color temperature of filament 100b at a, as... Figure 6 Steps S1 and S2 are shown respectively. In the subsequent second stage, the color temperature of filament 100b is increased from c to d, while the color temperature of filament 100a is maintained at b, as shown. Figure 6 Steps S3 and S4 are shown respectively.

[0075] Figure 5b It shows the relationship with Figure 5a Another slightly different pre-selected control scheme is shown. Here, in the first stage, the color temperature of filament 100a increases from a to b, while the color temperature of filament 100b decreases from a to c. Similarly, Figure 5b This stage corresponds to Figure 6 Steps S1 and S2 in the flowchart. In the subsequent second stage, the color temperature of filament 100b is increased, while the color temperature of filament 100a is decreased from b to d. Figure 5b This stage corresponds to Figure 6 Steps S3 and S4.

[0076] Figure 5c An alternative scheme to the pre-selected control scheme is shown. Here, in the first stage, the color temperature of filament 100a is increased from a to b, while the color temperature of filament 100b is slightly increased from a to c. Similarly, Figure 5b This stage corresponds to Figure 6Steps S1 and S2 in the flowchart. In the subsequent second stage, the color temperature of filament 100b is increased, while the color temperature of filament 100a is slightly increased from b to d. Figure 5b This stage corresponds to Figure 6 Steps S3 and S4. It should be noted that the phrase "slightly increased" implies that the second color temperature in stage 1 and the first color temperature in stage 2 are increased less than the first color temperature and the second color temperature, respectively.

[0077] Points b and c can coincide in time (e.g.) Figure 5a (As shown in the diagram). This means that in Figure 6 In this process, steps S1 and S2 will be precisely synchronized in time, and steps S3 and S4 will begin simultaneously. Alternatively, the stage of increasing the color temperature of filament 100b can be performed. Figure 6 Step S3) can be advanced or delayed relative to the time point (point b) when the color temperature of filament 100a reaches its maximum value. According to the latter alternative, this would translate to steps S3 and S4 starting at different time points. Figure 5b A control scheme is shown in which the color temperature of the increased filament 100b is delayed in time relative to point b. In other words, in a later embodiment of the control scheme, Figure 6 Step S3 is delayed relative to step S4.

[0078] Figure 5d It shows Figure 5b A similar pre-selected control scheme is shown, in which, in the first stage, the color temperature of filament 100a increases from a to b, while the color temperature of filament 100b decreases from a to c, and in the subsequent second stage, the color temperature of filament 100b increases, while the color temperature of filament 100a decreases from b to d. However, in Figure 5d In the illustration, CT1 low and CT2 low The lack of overlap leads to ΔCT start Greater than zero. Similarly, CT1 high and CT2 high The lack of overlap leads to ΔCT end Greater than zero. Preferably, CT1 low and CT2 low The difference between (ΔCT) start ) and CT1 high and CT2 high The difference between (ΔCT) end The value is less than 500K, more preferably less than 300K, and most preferably less than 100K. Among the optional pre-selected control schemes, the following may occur: Figure 5a , Figure 5b , Figure 5c and Figure 5d Different combinations and / or other variations.

[0079] Preferably, the second stage of the pre-selected control scheme is executed after the first color temperature is increased to at least 400K, more preferably 500K, and most preferably 600K. According to... Figures 5a to 5d The diagram will be transformed into "a-b>400K, or a-b>500K, or a-b>600K".

[0080] Figure 7 A graph depicting the variation of the difference between the first and second color temperatures (ΔCT) over time is presented. It is evident that ΔCT is not constant and varies with time. Figure 6 In the first stage of the pre-selected control scheme described in steps 1 and 2, ΔCT increases with time. However, when the second stage is initiated—as... Figure 6 As described in steps 3 and 4—ΔCT decreases over time. Figure 7 In the diagram, it can be observed that ΔCTstart and ΔCTend do not correspond to the same value, and ΔCTstart is greater than ΔCTend. However, in an alternative embodiment, ΔCTstart may be higher, or alternatively equal to ΔCTend. If ΔCTstart and / or ΔCTend are not equal to zero, then CT1 low and CT2 low and / or CT1 high and CT2 high Non-overlapping, which means that in the diagram of Figure 5, at points a and / or d of the pre-selected control scheme, CT1 low Not equal to CT2 low and / or CT1 high Not equal to CT2 high Therefore, corresponding to Figure 7 The illustrated embodiment corresponds to Figure 5d The pre-selected control scheme. Alternatively, if ΔCTstart and / or ΔCTend are zero, then ΔCTstart and / or ΔCTend are not equal to zero, then CT1 low and CT2 low and / or CT1 high and CT2 high Non-overlapping. CT1 low and CT2 low and CT1 high and CT2 high Implementations where both overlap correspond to Figures 5a to 5c The pre-selected control scheme shown can also be implemented where the slopes of the plotted lines in stages 1 and 2 have equal absolute values. In this case, stages 1 and 2 of the pre-selected control scheme are executed at equal rates. Alternatively, the absolute values ​​of the slopes can be different. In this case, the execution rates of stages 1 and 2 will be different.

[0081] Those skilled in the art will recognize that the present 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, the number of LED filaments and their detailed arrangement may differ from those shown herein.

[0082] 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 practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not imply that combinations of these measures cannot be advantageously used.

Claims

1. A light-emitting device (10) configured to emit light having a total color temperature (CTtot), the light-emitting device (10) comprising: At least one first light-emitting diode (LED) filament (100a), and At least one second LED filament (100b). Each of the at least one first LED filament (100a) and the at least one second LED filament (100b) includes an elongated carrier (120) and an array of light-emitting diodes (100) mounted on the carrier (120); and A controller (15) is used to individually control the at least first LED filament (100a) and the at least second LED filament (100b). The at least one first LED filament (100a) is arranged to emit light of a uniform color having a first color temperature CT1, wherein the first color temperature is determined by the emission of light from CT1. low To CT1 high Controllable within the first color temperature range, The at least one second LED filament (100b) is arranged to emit light of a uniform color having a second color temperature CT2, wherein the second color temperature is the color temperature emitted from CT2. low To CT2 high The second color temperature range is controllable, and The controller (15) is configured to change the first color temperature and the second color temperature by simultaneously controlling all LEDs of each LED filament, such that all LEDs of the LED filament emit light of the same color temperature, and to control the total color temperature CTtot from the first total color temperature CTtot,1 to the second total color temperature CTtot,2 by independently controlling the first color temperature and the second color temperature according to a pre-selected control scheme, such that the difference ΔCT between the first color temperature and the second color temperature is not constant during the change of CTtot from CTtot,1 to CTtot,2, to produce the flame-like appearance of the light-emitting device, wherein the independent control of the first color temperature and the second color temperature is achieved by independently controlling the relative intensity of each color of LED in the LED array in the respective LED filament.

2. The light-emitting device according to claim 1, wherein CT1 low and CT2 low Below 2500K.

3. The light-emitting device according to claim 1, wherein CT1 low and CT2 low Below 2400K.

4. The light-emitting device according to claim 1, wherein CT1 low and CT2 low Below 2300K.

5. The light-emitting device according to claim 1, wherein CT1 high and CT2 high Above 2700K.

6. The light-emitting device according to claim 1, wherein CT1 high and CT2 high Above 2900K.

7. The light-emitting device according to claim 1, wherein CT1 high and CT2 high Above 3500K.

8. The light-emitting device according to claim 1, wherein the first color temperature range and the second color temperature range overlap.

9. The light-emitting device according to claim 8, wherein for the first total color temperature (CTtot,1), the first color temperature (CT1) is equal to the second color temperature (CT2).

10. The light-emitting device according to claim 8 or 9, wherein the first color temperature range and the second color temperature range are the same.

11. The light-emitting device according to any one of claims 1-9, wherein the controller is configured to change the first color temperature and the second color temperature by simultaneously controlling the LED array of each LED filament.

12. The light-emitting device according to any one of claims 1-9, wherein the controller is configured to change the first color temperature and the second color temperature by individually controlling the LED array of each LED filament.

13. The light-emitting device according to any one of claims 1-9, wherein, in order to increase the total color temperature, the pre-selected control scheme includes: In the first stage, the difference (ΔCT) is increased, and In the subsequent second stage, the difference (ΔCT) is reduced.

14. The light-emitting device according to claim 13, wherein the second stage is initiated when the color temperature of the at least one first filament has increased by at least 400K.

15. The light-emitting device according to claim 13, wherein the second stage is initiated when the color temperature of the at least one first filament has increased by at least 500K.

16. The light-emitting device according to claim 13, wherein the second stage is initiated when the color temperature of the at least one first filament has increased by at least 600K.

17. The light-emitting device according to any one of claims 1-9 and 14-16, wherein the total number of first LED filaments is greater than the total number of second LED filaments.

18. The light-emitting device according to claim 1, wherein the total number of the first LED filaments is less than the total number of the second LED filaments.

19. The light-emitting device according to any one of claims 1-9, 14-16 and 18, wherein the LEDs of the first LED filament and the second LED filament are configured to emit white light.

20. The light-emitting device according to any one of claims 1-9, 14-16 and 18, wherein the LEDs of the first LED filament and the second LED filament are red, green and blue LEDs.

21. A modified light bulb, comprising: At least one light-emitting device according to any one of the preceding claims, a light-transmitting housing at least partially surrounding the at least one first LED filament and the at least one second LED filament, and a connector for electrically and mechanically connecting the bulb to a socket.

22. A method for controlling a light-emitting device, the light-emitting device comprising at least one first LED filament and at least one second LED filament, the light-emitting device being configured to emit light having a total color temperature (CTtot), the method comprising: The first color temperature of the at least one first LED filament and the second color temperature of the at least one second LED filament are controlled by independently controlling the relative intensity of each color LED in the LED array within the respective LED filaments, thereby controlling the overall color temperature to achieve a preset value and producing the flame-shaped appearance of the light-emitting device. The control is performed according to a pre-selected control scheme, such that the difference between the first color temperature and the second color temperature is not constant during changes in the total color temperature.

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