LED filament and LED filament lamp
By setting multiple individually controllable blue LED arrays on the LED filament and using encapsulant of different concentrations to control light conversion, the problem of narrow CCT range of LED filament lamps is solved, achieving wider color temperature control and high-temperature light emission.
Patent Information
- Application Number
- CN202480019939.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-03-20
- Filing Date
- 2024-03-12
- Publication Date
- 2025-11-18
AI Technical Summary
Existing LED filament lamps have a narrow CCT controllability range and cannot provide high-temperature light.
A single, controllable array of multiple blue LEDs is mounted on a slender carrier. The light conversion degree of different arrays is controlled by covering them with light-emitting encapsulant dots of varying concentrations. This includes transparent or semi-transparent encapsulant dots to reduce light conversion. Combined with a transparent carrier design, this allows for the mixing and adjustment of light.
The CCT adjustable range of LED filament lamps has been expanded, providing a wider range of color temperature control, including high-temperature light emission.
Smart Images
Figure CN120981684A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present invention relates to an LED filament comprising an elongated carrier and a plurality of LEDs mounted on the carrier and to an LED filament lamp, i.e. a lamp comprising an envelope containing the LED filament and a connector for mechanical and electrical connection of the lamp. BACKGROUND
[0002] In recent years, LEDs (Light Emitting Diodes) have become the dominant light source in many applications due to their impressive energy efficiency. One example is the LED lamp, which has largely replaced the incandescent lamp with its heated metal filament lamp filament in a gas tight envelope.
[0003] One disadvantage of LED lamps is that the emitted light can be perceived as different from the light emitted by an incandescent lamp. Therefore, various efforts have been made to make LED lamps look like incandescent lamps. One specific result of these efforts is the LED filament, i.e. a plurality of LEDs arranged on an elongated carrier and covered by a luminescent encapsulant. The light emitted from the LED filament largely looks like the light emitted by a metal filament in an incandescent lamp.
[0004] For aesthetic and light distribution purposes, a bulb with an LED filament, called LED filament lamp, is designed to look like a traditional incandescent lamp bulb with one or several visible LED filaments. LED filament lamps have become increasingly popular and are commercially available as household lamps as well as commercial lamps.
[0005] Some LED filament lamps are controllable with respect to color point and color temperature and for this purpose, there are LED filaments with two separately controllable strings of blue LEDs, where the LEDs in one string are covered by small dots of high luminosity encapsulant. All LEDs are then covered by a general encapsulant with a slightly lower luminosity than the small dots. As a result, the two strings of LEDs will be exposed to different amounts of light emission, thus providing white light of different color temperatures (correlated color temperature, CCT). By controlling the two strings, the overall color temperature of the LED filament can be controlled.
[0006] A disadvantage of such controllable LED filaments is that the CCT range is rather limited, typically 2200 K to 2700 K, and that high temperature light cannot be provided. SUMMARY
[0007] It is an object of the present invention to provide an LED filament with improved CCT controllability.
[0008] This object and other objects are achieved by an LED filament providing LED filament light, the LED filament comprising an elongated carrier having a plurality of blue LEDs mounted at a mounting side of the elongated carrier, wherein the plurality of blue LEDs comprises a first individually controllable array of blue LEDs emitting a first blue LED light, a second individually controllable array of blue LEDs emitting a second blue LED light, and a third individually controllable array of blue LEDs emitting a third blue LED light. The LED filament further comprises an elongated encapsulant layer covering all LEDs in the first individually controllable array and all LEDs in the second individually controllable array, the elongated encapsulant layer being formed of a first luminescent material having luminescent particles at a first concentration CI.
[0009] The blue LEDs in the second individually controllable array are covered by first encapsulant dots, the first encapsulant dots being formed of a second luminescent material having luminescent particles at a second concentration C2, wherein C2 > CI, and the blue LEDs in the third individually controllable array are covered by second encapsulant dots, wherein (i) the second encapsulant dots are free of luminescent material, or (ii) the second encapsulant dots are formed of a third luminescent material having luminescent particles at a third concentration C3, and wherein C3 < CI. The second encapsulant dots are at least partially covered by the elongated encapsulant layer.
[0010] A “blue” LED is here intended to mean an LED that is configured to emit light in the blue region of the visible spectrum.
[0011] By covering the LEDs in the third array with encapsulant dots that have less luminescence than the third luminescent material, the light emitted from the LEDs in the third array will be subject to less luminescence. As a result, the blue light will be less wavelength converted, resulting in a higher color temperature. The second encapsulant dots can be completely non-luminescent, but can also luminesce to some extent, but less than the first luminescent material.
[0012] In this case, the concentration C3 of luminescent particles in the third luminescent material is preferably less than 0.8 times the concentration CI of luminescent particles in the first luminescent material, i.e. C3 / C1 < 0.8. More preferably, C3 / C1 < 0.5, and most preferably, C3 / C1 < 0.3.
[0013] The concentration CI of luminescent particles in the first luminescent material is preferably less than 0.8 times the concentration C2 of luminescent particles in the second luminescent material, i.e. CI / C2 < 0.8. More preferably, CI / C2 < 0.5, and most preferably, CI / C2 < 0.3.
[0014] The second encapsulant dots can be transparent such that they do not scatter light emitted by the blue LEDs in the third array. Alternatively, the second encapsulant dots can be translucent such that they diffuse light emitted by the blue LEDs in the third array.
[0015] Note that the light ultimately emitted from the LED filament (referred to as LED filament light) will be a mixture of contributions from one or more of the first blue LED light, the first converted light, the second blue LED light, the second converted light, the third blue LED light, and the third converted light.
[0016] The thickness of the second encapsulant dots can be greater than the thickness of the first encapsulant dots such that the blue light from the LEDs in the third array is even less wavelength converted.
[0017] In some embodiments, the elongate encapsulant layer covers all of the LEDs in the third individually controllable array. However, in other embodiments, the thickness of the second encapsulant dots corresponds to or even exceeds the thickness of the luminescent encapsulant layer such that the encapsulant layer does not exceed the second encapsulant dots and does not cover the LEDs in the third individually controllable array. In this case, when the second encapsulant dots are non-luminescent, at least some of the light emitted from the blue LEDs in the third array will be emitted without any wavelength conversion.
[0018] The first luminescent material can comprise green-yellow phosphor particles and red phosphor particles. The second luminescent material can comprise red phosphor particles and optionally green-yellow phosphor particles. The third luminescent material (if present) can comprise green-yellow phosphor particles and can be free of red phosphor particles.
[0019] Note that the first luminescent material is configured to at least partially convert the first blue LED light, the second blue LED light, and / or the third blue LED light into the first converted light. In a similar manner, the second luminescent material is configured to at least partially convert the second blue LED light into the second converted light. Finally, the third luminescent material (if present) is configured to at least partially convert the third blue LED light into the third converted light.
[0020] The first blue LED light can have a first dominant peak wavelength λ1, the second blue LED light can have a second dominant peak wavelength λ2, and the third blue LED light can have a third dominant peak wavelength λ3. The dominant peak wavelengths can be relatively close together such that |λ2- λ1|≤ 20 nm and / or |λ3- λ2|≤ 20 nm However, preferably the dominant peak wavelengths are further apart such that |λ2- λ1|≥ 20 nm and / or |λ3- λ2|≥ 20 nmSuch separation of the main peak wavelengths can be advantageous. For example, the first main wavelength λ1 and the second main wavelength λ2 can be closer to the excitation maximum of the second luminescent material, thereby resulting in a higher (luminescent) conversion of the first luminescent point, while the third main wavelength λ3 can be further away from the excitation maximum. In this way, (relatively) less third blue LED light is converted into first converted light.
[0021] In an embodiment, the carrier is light transmissive (e.g. transparent), such that light emitted from the blue LEDs transmits through the carrier and is emitted out of a back side opposite the mounting side. In this case, the LED filament can further comprise a third encapsulant dot arranged on the back surface and aligned with the LEDs in the second array, a fourth encapsulant dot arranged on the back surface and aligned with the LEDs in the third array, and a second luminescent encapsulant layer arranged on the back surface and aligned with the first luminescent encapsulant layer.
[0022] The second elongated encapsulant layer can be formed of a fourth luminescent material having luminescent particles at a fourth concentration C4, the third encapsulant dot can be formed of a fifth luminescent material having luminescent particles at a fifth concentration C5, wherein C5 > C4, and the fourth encapsulant dot can be (i) free of luminescent material, or (ii) formed of a sixth luminescent material having luminescent particles at a sixth concentration C6, wherein C6 < C4.
[0023] It is noted that C1 ≠ C4, and / or C2 ≠ C5, and / or C3 ≠ C6.
[0024] A second aspect of the present invention relates to an LED filament lamp comprising an LED filament according to the first aspect of the present invention and a controller configured to individually control the first individually controllable array of blue LEDs, the second individually controllable array of blue LEDs and the third individually controllable array of blue LEDs to vary a correlated color temperature of the emitted LED filament light.
[0025] In some embodiments, the lamp further comprises an envelope enclosing the LED filament and a connector for mechanically and electrically connecting the LED filament lamp to a luminaire socket.
[0026] In some embodiments, the lamp further comprises an antenna functionally coupled to the controller of the LED filament lamp and configured to receive a user input from a remote device, wherein the controller is configured to individually control the first individually controllable array of blue LEDs, the second individually controllable array of blue LEDs and the third individually controllable array of blue LEDs based on the user input. BRIEF DESCRIPTION OF DRAWINGS
[0027] The present invention will be described in more detail with reference to the enclosed drawings, which show a currently preferred embodiment of the invention.
[0028] Fig. 1a is a perspective view of an LED filament according to the prior art.
[0029] Fig. 1b is a cross-sectional view of the LED filament in Fig. 1a.
[0030] Figures 2a to 2g is a cross-sectional view of an LED filament according to various embodiments of the present application.
[0031] Figure 3 is a perspective view of an LED filament lamp according to an embodiment of the present application. DETAILED DESCRIPTION
[0032] The LED filament in Figs. 1a-1b has an elongated and generally flat carrier 1 on which a plurality of blue LEDs 2a, 2b are mounted. The carrier 1 can be made of a rigid material such as ceramic or metal. Alternatively, it can be made of a flexible material such as plastic.
[0033] The LEDs 2a, 2b are arranged in two LED arrays, which are individually connected by means of respective electrically conductive paths 3a, 3b also provided on the carrier 1. All LEDs 2a, 2b are further covered by a layer 4 of a luminescent encapsulant, which is formed of a first material comprising phosphor particles, for example. The LEDs 2b in the second array are also covered by a dot 5 of a luminescent encapsulant, which is formed of a second material comprising phosphor particles, for example. The layer 4 and the dot 5 serve to convert the light emitted from the LEDs 2a, 2b from a blue wavelength to a white color.
[0034] The second material (in the dot) has a higher concentration of phosphor particles than the first material (in the layer), so that the light emitted from the LEDs 2b in the second array will be subject to more wavelength conversion than the light emitted by the LEDs 2a in the first array. Thus, the light emitted from the LEDs 2a will provide a first, higher color temperature T2 (more blue), while the LEDs 2b in the second array will provide a second, lower color temperature Tl (less blue).
[0035] By controlling the two LED arrays separately, the overall color temperature of the LED filament light emitted by the LED filament can be adjusted between the two extreme points Tl and T2.
[0036] Embodiments of the present application will now be described with reference to Figures 2a to 2g Figs. 1a-1b.
[0037] Figure 2a The LED filament 10 in Fig. 1a has a carrier 11 and three arrays 12a, 12b, 12c of blue LEDs mounted on a mounting side 11a of the carrier 11. Each LED array is provided with a separate electrical connection (not shown) and is individually controllable.
[0038] In the illustrated example, all LEDs 12a, 12b, 12c are covered by a layer 14 of a luminescent encapsulant made of a first luminescent material containing luminescent particles (e.g. phosphor particles) at a concentration CI. Furthermore, LEDs 12b in the second group are covered by an encapsulant dot 15 of a second luminescent material containing luminescent particles (e.g. phosphor particles) at a second concentration C2. Layer 14 and dot 15 can be similar to layer 4 and dot 5 in Fig. la, such that light emitted from LEDs 12a will have a color temperature T2 and light emitted from LEDs 12b will have a color temperature Tl.
[0039] Furthermore, LEDs 12c in the third group are covered by an encapsulant dot 16 formed of a material having a lower luminosity than layer 14. Thus, light emitted by LEDs 12c in the third array will undergo less wavelength conversion than LEDs 12a, 12b in the first and second arrays, and thus have an even higher color temperature T3 (even more blue). Thus, LED filament 10 can be controlled to emit light within a larger color temperature range (Tl to T3).
[0040] In one embodiment, dot 16 is formed of a material that is completely non-luminescent and can be transparent or diffusive, for example. In another embodiment, dot 16 is formed of a third luminescent material containing luminescent particles, e.g. phosphor particles, at a third concentration C3.
[0041] By way of illustration only, the first luminescent material in layer 14 can include green-yellow phosphor particles and red phosphor particles. The second luminescent material in dot 15 can include red phosphor particles and optionally green-yellow phosphor particles. The third luminescent material (if present in dot 16) can include green-yellow phosphor particles and can be free of red phosphor particles.
[0042] As shown in Figure 2b Dot 16 covering LEDs 12c can have a thickness D2 that is greater than the thickness Dl of dot 15. Thus, light emitted from LEDs 12c will pass through less of the luminescent layer 14 and will undergo even less wavelength conversion. Indeed, as shown in Figure 2c Dot 16 can have a thickness D2 that corresponds to the thickness D3 of layer 14. Or even, as shown in Figure 2d Exceeding the thickness D3 of layer 14.
[0043] Turning to Figure 2e , LED filament 10e is similar to Figure 2dThe difference lies in the filament, where the encapsulant point 18 surrounds the LED 12c and gradually narrows towards the LED 12c. For example, point 18 can be conical or pyramidal. This shape can ensure even lower levels of wavelength conversion.
[0044] Figure 2f It shows the relationship with Figure 2d The LED filament is similar to that of the LED filament in this example, but it incorporates additional, separately controllable LED arrays that emit different colors of light; in the illustrated case, this is an array of red LEDs 12d and green LEDs 12e. The additional controllable LED arrays can further improve the color temperature control of the LED filament. Furthermore, the additional LED arrays offer the opportunity for significant enhancements in color control, which, combined with improved color temperature control, can be particularly beneficial.
[0045] Figure 2g The diagram shows a transparent LED filament in a carrier 11, meaning that light emitted by LEDs 12a, 12b, and 12c will also be transmitted through the carrier to be emitted on the back side 11b, opposite to the mounting side 11a. To ensure that the light emitted on the back side has the same or at least similar color temperature as the light emitted on the front side, a light-emitting layer 19, similar to layer 14, is also provided on the back side. Furthermore, light-emitting points 20 and 21, corresponding to points 15 and 16, are provided on the back side, aligned with LEDs 12b and 12c, respectively. Since the amount of light reaching the back side will be less than the amount of light emitted from the front side, the thicknesses of points 20 and 21 and the thickness of layer 19 can be less than the corresponding thicknesses of points 15 and 16 and layer 14. Alternatively, the thicknesses can be the same, but the concentrations of phosphor particles C4 in layer 19 and / or the concentrations of phosphor particles C5 and C6 in points 15 and 16 can be different compared to concentrations C1, C2, and C3, respectively.
[0046] Figure 3 The LED filament lamp 30 generally comprises a light-transmitting housing 31 and a connector 32 configured to electrically and mechanically connect the lamp to a socket 33. Here, the connector 32 is a threaded connector conforming to existing bulb socket standards (e.g., E27). The housing 32 can be made of glass or plastic and, depending on the desired illumination, can be transparent (light-transmitting) or diffused. One or more (in the illustrated case, four) [unclear - possibly referring to specific components or features] are arranged inside the housing 32 according to [unclear - possibly referring to specific components or features]. Figures 2a to 2g One example is the LED filament 10.
[0047] The lamp 30 also includes a driver circuit 34 for driving an individually controllable LED array and a controller 35 for controlling the driver circuit 35. The controller 35 can remotely receive control signals via an antenna 36. These control signals can be generated by user input from a remote device, such as a handheld device (e.g., a smartphone).
[0048] The skilled person realizes that the present application is in no way limited to the preferred embodiments described above. On the contrary, many modifications and changes are possible within the scope of the appended claims. For example, the present application is not limited to blue LEDs and light emitting encapsulants. The principles of the present application are generally applicable to any type of LED, wherein different arrays of LEDs are subjected to different amounts of wavelength conversion.
Claims
1. An LED filament (10) for providing LED filament light, comprising: An elongate carrier (11); A plurality of blue LEDs (12a, 12b, 12c), mounted on the mounting side (11a) of the elongate carrier, wherein the plurality of blue LEDs (12a, 12b, 12c) comprises: A first individually controllable array of blue LEDs (12a) emitting first blue LED light, A second individually controllable array of blue LEDs (12b) emitting second blue LED light, and A third individually controllable array of blue LEDs (12c) emitting third blue LED light; and An elongate encapsulant layer (14), covering all of the LEDs (12a) in the first individually controllable array and all of the LEDs (12b) in the second individually controllable array, the elongate encapsulant layer being formed from a first light-emitting material having luminescent particles at a first concentration C1, Wherein the blue LEDs (12b) in the second individually controllable array are covered by a first encapsulant dot (15) formed from a second light-emitting material having luminescent particles at a second concentration C2, where C2 > C1, and Wherein the blue LEDs (12c) in the third individually controllable array are covered by a second encapsulant dot (16); wherein: (i) The second encapsulant dot does not contain a light-emitting material, or (ii) The second encapsulant dot is formed from a third light-emitting material having luminescent particles at a third concentration C3, and where C3 < C1, and Wherein the second encapsulant dot is at least partially covered by the elongate encapsulant layer (14).
2. The LED filament according to claim 1, wherein C1 / C2 < 0.5 and / or C3 / C1 < 0.
5.
3. The LED filament according to any one of the preceding claims, wherein the second encapsulant dot does not contain a light-emitting material, and, Wherein the second encapsulant dot (16) is translucent or comprises a light-scattering material.
4. The LED filament according to any one of the preceding claims, wherein the thickness (D2) of the second encapsulant dot (16) is greater than the thickness (D1) of the first encapsulant dot (15).
5. The LED filament according to any one of the preceding claims, wherein the elongate encapsulant layer (14) covers all of the LEDs (12c) in the third individually controllable array.
6. The LED filament according to any one of claims 1 to 4 of the preceding claims, wherein the thickness (D2) of the second encapsulant dot (16) corresponds to or exceeds the thickness (D3) of the light-emitting encapsulant layer (14).
7. The LED filament according to any one of the preceding claims, wherein the first light-emitting material comprises green-yellow phosphor particles and red phosphor particles, and / or wherein the second light-emitting material comprises red phosphor particles and optionally comprises green-yellow phosphor particles.
8. The LED filament according to any one of the preceding claims, wherein when the second encapsulant point is formed of a third luminescent material having luminescent particles of a third concentration of C3, the third luminescent material comprises green-yellow phosphor particles and does not contain red phosphor particles.
9. The LED filament according to any one of the preceding claims, wherein the first blue LED light has a first peak wavelength λ1, the second blue LED light has a second peak wavelength λ2, and the third blue LED light has a third peak wavelength λ3, and wherein |λ2-λ1|≥20 nm and / or |λ3-λ2|≥20 nm .
10. The LED filament according to any one of the preceding claims, wherein the elongated carrier (11) is light-transmitting, such that light from the blue LEDs (12a, 12b, 12c) is also emitted from the back side (11b) opposite to the mounting side (11a), and wherein the LED filament further comprises: The third encapsulant point (20) is disposed on the rear surface and aligned with the blue LED (12b) of the second separately controllable array. The fourth encapsulant point (21) is disposed on the rear surface and aligned with the blue LED (12c) of the third separately controllable array, and A second elongated light-emitting encapsulant layer (19) is disposed on the back side (11b) and aligned with the first light-emitting encapsulant layer (14).
11. The LED filament according to claim 10, wherein the second elongated encapsulant layer (19) is formed of a fourth luminescent material having luminescent particles of a fourth concentration of C4. The third encapsulant point (20) is formed of a fifth luminescent material having luminescent particles of a fifth concentration C5, wherein C5 > C4, and The fourth encapsulant point (21) is mentioned above. (i) Does not contain luminescent materials, or (ii) Formed from a sixth luminescent material, said sixth luminescent material having luminescent particles of a sixth concentration of C6, wherein C6 <C4。 12. The LED filament according to claim 11, wherein C1≠C4, and / or C2≠C5, and / or C3≠C6.
13. An LED filament lamp (30), comprising: LED filament according to any one of the preceding claims, and A controller (35), wherein the controller is configured to individually control a first individually controllable array of the blue LEDs (12a), a second individually controllable array of the blue LEDs (12b), and a third individually controllable array of the blue LEDs (12c) to change the correlated color temperature of the LED filament light.
14. The LED filament lamp (30) according to claim 13 further comprises: The casing (31) at least partially surrounds the LED filament, and Connector (32) for mechanically and electrically connecting the LED filament lamp to a socket of the luminaire.
15. The LED filament lamp (30) according to claim 13 or 14, further comprising: The antenna (36) is functionally coupled to the controller (35) of the LED filament lamp and is configured to receive user input from a remote device; The controller (35) is configured to individually control a first individually controllable array of the blue LEDs (12a), a second individually controllable array of the blue LEDs (12b), and a third individually controllable array of the blue LEDs (12c) based on the user input.