LED lamp filament

Abstract

An LED filament (1) configured to emit LED filament light (8, 9) in operation, and comprising: a light transmissive elongate carrier (2) comprising a first main surface (4) and a second main surface (5); an array of a plurality of N number of LEDs (3) configured to emit LED light (10) in operation and arranged on the first major surface (4) of the light transmissive elongate carrier (2); the encapsulant comprises an elongate encapsulant (6) of luminescent material (12) arranged to cover the plurality of LEDs (3) and at least a portion of the first major surface (4) and configured for at least partially converting the LED light (10) into converted light (11); and a partially light transmissive layer (7; 16) disposed on the light transmissive elongate carrier (2) configured to perform one or more of reflection and absorption of at least a portion (14) of one or more of the LED light (10) and the converted light (11), and configured to provide non-uniform transmission of light in a wavelength range of 400 nm to 800 nm.

Description

Technical Field

[0001] This invention relates to an LED filament configured to emit LED filament light during operation. The LED filament includes: a light-transmitting elongated carrier including a first main surface and a second main surface; a plurality of LEDs configured to emit LED light during operation and disposed on the first main surface of the light-transmitting elongated carrier; and an elongated encapsulation including a light-emitting material, the elongated encapsulation being disposed to cover at least a portion of the plurality of LEDs and the first main surface, and the elongated encapsulation being configured to at least partially convert the LED light into converted light. The invention also relates to luminaires or lighting devices including such an LED filament. Background Technology

[0002] The lighting trend is towards LED filament lamps. LED filament lamps are lamps designed to resemble traditional incandescent bulbs, featuring visible filaments for aesthetic and light distribution purposes, but with the high efficiency of light-emitting diodes.

[0003] US2022 / 0186889A1 discloses a light-emitting diode (LED) filament. The LED filament includes an elongated substrate and a plurality of light-emitting diodes (LEDs) mechanically coupled to the substrate. The LED filament also includes: a partially transparent package that encapsulates the plurality of LEDs and at least partially encapsulates the substrate; and a plurality of at least partially reflective particles disposed on the outer surface of the package.

[0004] The invention in WO2022 / 253735 relates to an LED filament configured to provide LED filament light (A, B) and includes an elongated carrier comprising a first elongated edge portion and a second elongated edge portion disposed at a distance from the first elongated edge portion, a first surface, and a second surface disposed opposite to the first surface, the first and second surfaces being delimited by the first and second edge portions. The LED filament also includes a plurality of first light-emitting diodes (LEDs) distributed along the first surface of the elongated carrier, the plurality of first LEDs being configured to emit first LED light. The LED filament further includes a first at least partially transparent elongated layer and a second elongated reflective layer, the first at least partially transparent elongated layer encapsulating or covering the plurality of first LEDs and at least partially encapsulating or covering the first surface of the elongated carrier, the second elongated reflective layer being arranged asymmetrically to encapsulate or cover the first at least partially transparent elongated layer.

[0005] The aim is to improve the performance, functionality, and / or appearance of LED filament lamps.

[0006] It is also desirable to provide an LED filament that can be used to obtain a desired target color point based on existing color points in a simple and direct manner. Summary of the Invention

[0007] One object of the present invention is to overcome this problem and to provide an LED filament and LED filament luminaire with improved performance, functionality and / or appearance.

[0008] A further object of the present invention is to provide an LED filament that allows for the simple and direct acquisition of a desired target color point based on existing color points.

[0009] According to a first aspect of the invention, the invention and other objectives are achieved by means of an LED filament configured to emit LED filament light in operation. The LED filament comprises: a light-transmitting elongated carrier including a first main surface and a second main surface opposite to the first main surface; an array of N LEDs configured to emit LED light in operation and disposed on the first main surface of the light-transmitting elongated carrier; an elongated encapsulation including a light-emitting material, the elongated encapsulation being disposed to cover at least a portion of the plurality of LEDs and the first main surface, and the light-emitting material being configured to at least partially convert the LED light into converted light; and a partially light-transmitting layer disposed on the light-transmitting elongated carrier, the partially light-transmitting layer being configured to perform one or more of reflection and absorption on at least a portion of one or more of the LED light and the converted light, and including non-uniform transmission of light in a wavelength range from 400 nm to 800 nm, for example, non-uniform transmission of blue, green and red light.

[0010] It should be noted that the LED array comprises a plurality of N LEDs, where N is an integer of 2 or more. An LED filament is provided by means of such an LED filament, and particularly by providing a partially transparent layer configured to perform one or more of reflection and absorption on at least a portion of one or more of the LED light and the converted light, and most importantly including non-uniform transmission of light in the wavelength range of 400 nm to 800 nm, by means of which the color point of the LED filament light emitted by the LED filament can be corrected or shifted.

[0011] Therefore, the desired target color point can be obtained based on the existing color point in a simple and direct way.

[0012] In addition, this LED filament is provided to have at least one of improved performance, improved functionality and improved appearance.

[0013] A portion of the light-transmitting layer may be disposed on one or both of the second main surface of the elongated carrier and the first main surface of the elongated carrier.

[0014] This results in LED filaments with improved performance and appearance. If the partial light-transmitting layer is disposed on the second main surface, it is easier to manufacture the LED filament because there are no LEDs and / or electrical tracks on the second main surface. If the partial light-transmitting layer is disposed on the first main surface, improved light recycling can be achieved.

[0015] The partially transparent layer can be configured to be at least a portion of one or more of the LED light and the converted light, and the partially transparent layer can be one or more of the reflective layer and the dichroic mirror.

[0016] Thus, the partially translucent layer is configured not only to correct the color point of the LED filament light, but also to prevent light loss during color point correction. In particular, light loss is prevented by using a reflective partially translucent layer, as such a layer is more efficient than a corresponding light-absorbing layer.

[0017] The LED light emitted by an array of N LEDs can have a (primary) peak wavelength in a first wavelength range from 430 nm to 490 nm. The converted light can include green-yellow light with a (primary) peak wavelength in a second wavelength range from 510 nm to 580 nm and red light with a (primary) peak wavelength in a third wavelength range from 600 nm to 680 nm. A portion of the light-transmitting layer can have a first (average) reflectivity R1 in the first wavelength range, a second (average) reflectivity R2 in the second wavelength range, and a third (average) reflectivity R3 in the third wavelength range, wherein the second reflectivity R2 is higher than the first reflectivity and / or the third reflectivity R3 is higher than the first reflectivity R1. That is, R2 > R1 and / or R3 > R1.

[0018] Reflectivity R1, R2, and / or R3 can be average reflectivity. Reflectivity R1, R2, and R3 typically depend on the angle at which they are measured. In this case, it should be understood that reflectivity R1, R2, and R3 are measured in directions perpendicular to the reflective surface or layer in question.

[0019] Thus, an LED filament is obtained that provides improved performance, especially when using multiple N LEDs with an emission peak wavelength in a first wavelength range from 430 nm to 490 nm.

[0020] The peak wavelength of any one or more of the LED light, green-yellow light, and red light emitted by an array of N LEDs can be the dominant peak wavelength.

[0021] As a result, LED filaments with particularly improved performance were obtained.

[0022] The luminescent material may include a first phosphor and a second phosphor.

[0023] Thus, LED light can be converted by the luminescent material to obtain converted light with two different peak wavelengths, and the phosphor can be selected according to the two different peak wavelengths required for a specific application.

[0024] The first phosphor and the second phosphor can be YAG and KSF, respectively.

[0025] This phosphor is particularly suitable for converting LED light into green-yellow light and red light, respectively.

[0026] The first reflectivity R1 can be less than 20%, preferably less than 15%, more preferably less than 10%, and most preferably less than 5%, wherein R2-R1≥30%, and wherein R3-R1≥30%.

[0027] The rationale for the above selection of reflectivities R1, R2, and R3 is as follows. Blue LED light is primarily emitted from the LEDs of the LED array in a direction away from the light output surface of the LEDs. Some of the LED light is scattered in other directions by phosphors and / or light-scattering materials, including in the direction of the elongated carrier. The converted light is emitted in all directions and is therefore directed more towards the elongated carrier than the blue LED light. Therefore, a higher reflectivity R2 and R3 for the converted light is desired compared to the reflectivity R1 of the LED light.

[0028] The second reflectivity R2 and the third reflectivity R3 can satisfy the relationship 1.2≥R2 / R3≥0.8.

[0029] This achieves a fairly similar ratio between the green-to-yellow conversion light and the red conversion light emitted from different sides of the LED filament.

[0030] LED filament light can be white light with a correlated color temperature (CCT) in the range of 1500K to 6500K or 1500K to 2500K and a CRI of at least 80.

[0031] Choosing a CCT in the range of 1500K to 2500K corresponds to extreme warm white light. In this case, the measures suggested above for reflectances R1, R2, and R3 respectively are particularly advantageous because the blue light content is low in extreme warm white light. For such a range, red light is far more abundant than green light, and green light is far more abundant than blue light.

[0032] LED filament light may include a first part and a second part, wherein the first part of the LED filament light is light emitted from the front side of the LED filament, and wherein the second part of the LED filament light is LED filament light that is transmitted through a partial light-transmitting layer and emitted from the back side of the LED filament, and wherein both the first part and the second part of the LED filament light are white light.

[0033] Therefore, an LED filament is provided that can emit white light from both sides or the main surface of the filament, thus ensuring a more uniform light output and a more uniform appearance of the LED filament, at least when it emits light.

[0034] The light-transmitting slender carrier can be a flexible light-transmitting slender carrier.

[0035] The translucent, slender carrier can be made of any of glass, sapphire, quartz, and polymers.

[0036] Thus, a carrier and LED filament with improved performance were obtained.

[0037] Slender encapsulations can be made of silicone.

[0038] Silicone is a particularly useful material for encapsulation of LED filaments, especially for stretchable LED filaments, because it is both flexible and stretchable, and also resistant to wear caused by LED light emitted from multiple LEDs.

[0039] LED filament light may include a first portion and a second portion, wherein the first portion of the LED filament light is light emitted from the front side of the LED filament, and wherein the second portion of the LED filament light is LED filament light transmitted through the light-transmitting layer and emitted from the back side of the LED filament, and wherein at least one of the following applies: the luminous flux of the second portion of the LED filament light is 0.2 to 0.6 times the luminous flux of the first portion of the LED filament light, and the first portion of the LED filament light includes a CCT within 300K of the correlated color temperature (CCT) of the second portion of the LED filament light.

[0040] By ensuring that the luminous flux of the second part of the LED filament light is 0.2 to 0.6 times that of the first part of the LED filament light, it is ensured that the luminous flux of the light emitted from the front side of the LED filament is significantly stronger than that emitted from the back side of the LED filament.

[0041] By ensuring that the first part of the LED filament light includes a CCT within 300K of the correlated color temperature (CCT) of the second part of the LED filament light, it is ensured that the light emitted from the front side of the LED filament and the light emitted from the back side of the LED filament have similar correlated color temperatures and therefore have similar appearances.

[0042] In both cases, LED filaments with improved performance and appearance were obtained.

[0043] Each LED in an array of N LEDs can emit light from (i) its top surface and (ii) its side surface and / or its bottom surface.

[0044] Because multiple LEDs, numbered N, each emit light from their side and / or bottom surfaces, significantly more blue light is directed into the light-transmitting layer. This results in an LED filament with improved performance.

[0045] The elongated package may include a non-emitting light-scattering material configured to scatter LED light.

[0046] In this way, more blue light is guided into part of the light-transmitting layer, resulting in an LED filament with improved performance.

[0047] LED filaments may also include an additional elongated package disposed between the elongated package and the light-transmitting elongated carrier, the additional elongated package including a non-emitting light-scattering material configured to scatter LED light.

[0048] In this way, more blue light is guided into part of the light-transmitting layer, resulting in an LED filament with improved performance.

[0049] The LED filament may also include a back-side encapsulation without luminescent material, wherein the back-side encapsulation is disposed on a second main surface of the LED filament opposite to the first main surface, and wherein the back-side encapsulation is disposed to cover at least a major portion of the light-transmitting layer and at least a portion of the second main surface.

[0050] Therefore, an LED filament is provided that improves the external optical coupling of LED filament light.

[0051] The back-side package may include a light-scattering material configured to scatter light transmitted through a portion of the light-transmitting layer.

[0052] Therefore, an LED filament is provided that improves the uniformity of LED filament light, particularly the uniformity of the second portion of the LED filament light.

[0053] The concentration of light-scattering material in the back-side package can be lower than the concentration of light-emitting material in the elongated package.

[0054] The concentration of the light-scattering material mentioned can be defined, for example, as the percentage volume of the light-scattering material relative to the total volume of the package under discussion.

[0055] For example, the light scattering material can be one or more of BaSO4, TiO2, and Al2O3.

[0056] This light-scattering material has been shown to be particularly suitable for improving the uniformity of LED filament light, especially the uniformity of the second part of the LED filament light.

[0057] The present invention also relates to LED luminaires or lighting devices comprising at least one LED filament according to the invention. The luminaire may include a base and a housing. The housing may at least partially surround the LED filament (or multiple LED filaments). The base may be configured to be electrically and mechanically connected to a socket of the lighting device. The lighting device may have a mounting portion for mounting the lighting device to a ceiling or wall.

[0058] It should be noted that the present invention relates to all possible combinations of the features described in the claims. Attached Figure Description

[0059] This and other aspects of the invention will now be described in more detail with reference to the accompanying drawings, which illustrate multiple embodiments of the invention.

[0060] Figure 1 A cross-sectional side view of an LED filament according to the present invention is shown.

[0061] Figure 2 A cross-sectional side view of an additional LED filament according to the present invention is shown.

[0062] Figure 3 It shows that according to Figure 1 The color spectrum of LED filaments.

[0063] Figure 4 It shows Figure 3 A close-up of section IV of the color map, and shows the results based on... Figure 1 An example of offset or correction of the color point obtained by the LED filament.

[0064] Figure 5 A cross-sectional side view of a luminaire including an LED filament according to the present invention is shown.

[0065] Figure 6 A graph illustrating the percentage of light transmission from a portion of the LED filament's light-transmitting layer according to the present invention as a function of the wavelength of the LED filament light is shown.

[0066] Figure 7 A graph showing the percentage of reflection of a portion of the light-transmitting layer of an LED filament according to the present invention as a function of the wavelength of the LED filament light is shown.

[0067] As shown in the figures, the dimensions of layers and regions are 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

[0068] 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.

[0069] Figure 1 A cross-sectional side view of an LED filament 1 according to an embodiment of the present invention is shown. The LED filament 1 is configured to emit LED filament light 8, 9 during operation. The LED filament light 8, 9 is white light. A portion 8 of the LED filament light 8, 9 is emitted from the front side 17 of the LED filament 1, and a portion 9 of the LED filament light 8, 9 is emitted from the back side 18 of the LED filament 1. Typically, and regardless of the embodiment, the LED filament 1 includes a light-transmitting elongated carrier 2, an LED array including a plurality of LEDs 3, an elongated encapsulation 6, and a partially light-transmitting layer 7.

[0070] The light-transmitting elongated carrier 2 includes a first main surface 4 and a second main surface 5. The first main surface 4 and the second main surface 5 are surfaces opposite to each other. The first main surface 4 and the second main surface 5 can be parallel surfaces. The light-transmitting elongated carrier 2 can be a flexible light-transmitting elongated carrier. For example, the light-transmitting elongated carrier 2 can be made of glass, sapphire, quartz, or polymer. The light-transmitting elongated carrier 2 can be translucent, preferably transparent. The light-transmitting elongated carrier 2 can have a light transmittance of at least 60%, preferably at least 70%, more preferably at least 80%, and most preferably at least 90%.

[0071] Multiple LEDs 3 are arranged in an array. The multiple LEDs 3 are configured to emit LED light 10 during operation. The multiple LEDs 3 comprise N LEDs, where N is an integer of 2 or greater. The multiple LEDs 3 are arranged on a first main surface 4 of a light-transmitting elongated carrier 2. Preferably, no LEDs are arranged on a second main surface 5. Each of the multiple LEDs 3 is configured to emit LED light 10 from its top surface 31 (…). Figure 1 ) Emit light. Each of the plurality of LEDs 3 may be further configured to emit light from one or both of its side surface 32 and its bottom surface 33.

[0072] An elongated package 6 is arranged to cover at least a portion of the plurality of LEDs 3 and the first main surface 4. The elongated package 6 may also be arranged to cover all of the first main surface 4. The elongated package 6 may be made of silicone resin. The elongated package 6 includes a light-emitting material 12. The light-emitting material 12 is configured to at least partially convert the LED light 10 into converted light 11. The light-emitting material 12 may include a first phosphor and a second phosphor. For example, the first phosphor may be YAG and the second phosphor may be KSF. The elongated package 6 may be a continuous package. The elongated package 6 may also include a non-light-emitting light-scattering material configured to scatter the LED light 10.

[0073] A portion of the light-transmitting layer 7 is arranged on the light-transmitting elongated carrier 2. More specifically, in Figure 1 In the illustrated embodiment, a partially transparent layer 7 is disposed on the second main surface 5 of the elongated carrier 2. The partially transparent layer 7 is configured to reflect at least a portion 14 of one or more of the LED light 10 and the converted light 11, or absorb at least a portion of one or more of the LED light 10 and the converted light 11, or partially reflect and partially absorb at least a portion of one or more of the LED light 10 and the converted light 11. The partially transparent layer 7 is configured to correct the color point of the LED filament light 8, 9. The partially transparent layer 7 is also configured to provide non-uniform transmission of light with a wavelength range from 400 nm to 800 nm. The partially transparent layer 7 may be a reflective layer configured to correct the color point of the LED filament light 8, 9. For example, the partially transparent layer 7 may be or include a dichroic mirror. The coverage of the partially transparent layer 7 on the elongated carrier 2, or on... Figure 1 In the embodiments shown, the coverage, particularly on the second main surface 5, can be at least 70%, preferably at least 80%, more preferably at least 90%, and most preferably at least 95%, for example, complete coverage.

[0074] As an example of the transmittance of part of the light-transmitting layer 7, Figure 6 A graph showing the percentage of transmittance of the partial light-transmitting layer 7 of the LED filament according to the present invention as a function of the wavelength of the LED filament light 8, 9 is shown.

[0075] LED light 10 can be blue light, and converted light 11 can be green-yellow light and red light. LED light 10 can have a peak wavelength in a first wavelength range from 430nm to 490nm (e.g., from 440nm to 465nm). The peak wavelength of LED light 10 can be the dominant peak wavelength.

[0076] The converted light 11 may include green-yellow light having a peak wavelength in a second wavelength range from 510 nm to 580 nm (e.g., from 540 nm to 570 nm) and red light having a peak wavelength in a third wavelength range from 600 nm to 680 nm (e.g., from 620 nm to 640 nm). The peak wavelength of the converted light 11 (such as the peak wavelength of one or both of the green-yellow light and the red light) may be the dominant peak wavelength.

[0077] The partially transparent layer 7 may have a first (average) reflectance R1 in a first wavelength range, a second (average) reflectance R2 in a second wavelength range, and a third (average) reflectance R3 in a third wavelength range. The second (average) reflectance R2 is higher than the first (average) reflectance R1 and / or the third (average) reflectance R3 is higher than the first (average) reflectance R1. That is, R2>R1 and R3>R1. The first (average) reflectance R1 may be lower than 20%, lower than 15%, lower than 10%, or even lower than 5%, R2-R1 may be greater than or equal to 30%, and R3-R1 may be greater than or equal to 30%. Moreover, the second reflectance R2 and the third reflectance R3 may satisfy the relationship 1.2≥R2 / R3≥0.8. This is in Figure 7 As shown in the figure, Figure 7 A graph showing the percentage of reflection of the partially transparent layer 7 of the LED filament according to the present invention as a function of the wavelength of the LED filament light 8, 9 is presented.

[0078] Furthermore, the absorption rate of a portion of the light-transmitting layer 7 is preferably less than 5%, more preferably less than 3%, and most preferably less than 2%, such as 1% or 0%.

[0079] LED filament lights 8 and 9 are white light. For example, LED filament lights 8 and 9 can be light with a correlated color temperature (CCT) in the range of 1500K to 6500K or a CCT in the range of 1500K to 2500K. For example, LED filament lights 8 and 9 can be light with a color rendering index (CRI) of at least 80. For example, LED filament lights 8 and 9 can be white light with a correlated color temperature (CCT) in the range of 2700K to 3500K and a CRI of at least 80. For example, LED filament lights 8 and 9 can be white light with a correlated color temperature (CCT) in the range of 4000K to 6500K and a CRI of at least 80.

[0080] The LED filament light 8, 9 includes a first portion 8 and a second portion 9. The first portion 8 of the LED filament light 8, 9 is light emitted from the front side 17 of the LED filament 1, i.e., in the direction away from the LED 3. Therefore, the first portion 8 of the LED filament light 8, 9 is light transmitted through the elongated package 6. The second portion 9 of the LED filament light 8, 9 is LED filament light transmitted through the partially transparent layer 7 and emitted from the back side 18 of the LED filament 1 opposite to the front side 17. The luminous flux of the second portion 9 of the LED filament light 8, 9 can be 0.2 to 0.6 times the luminous flux of the first portion 8 of the LED filament light 8, 9, or 0.3 to 0.5 times the luminous flux of the first portion 8 of the LED filament light 8, 9. Alternatively or additionally, the first portion 8 of the LED filament light 8, 9 can include a correlated color temperature (CCT) within 200K or 300K of the CCT of the second portion 9 of the LED filament light 8, 9.

[0081] Figure 2 A cross-sectional side view of an LED filament 100 according to another embodiment of the present invention is shown. The LED filament 100 and... Figure 1 The only difference of the LED filament 1 shown is the following features.

[0082] The LED filament 100 includes an additional light-transmitting layer 16. This additional light-transmitting layer 16 is disposed on an elongated carrier 2. More specifically, in Figure 2 In the embodiment shown, an additional portion of the light-transmitting layer 16 is arranged on a portion of the first main surface 4 of the elongated carrier 2.

[0083] Alternatively, a further portion of the light-transmitting layer 16 may be disposed on all the first main surfaces 4 of the elongated carrier 2. The further portion of the light-transmitting layer 16 is configured to reflect at least a portion of one or more of the LED light 10 and the converted light 11, or absorb at least a portion of one or more of the LED light 10 and the converted light 11, or partially reflect and partially absorb at least a portion of one or more of the LED light 10 and the converted light 11. The further portion of the light-transmitting layer 16 is further configured to provide non-uniform transmission of light in the wavelength range of 400 nm to 800 nm. The further portion of the light-transmitting layer 16 may be a reflective layer configured to correct the color point of the LED filament light 8, 9. For example, the further portion of the light-transmitting layer 16 may be or include a dichroic mirror. The coverage of the further portion of the light-transmitting layer 16 on the light-transmitting elongated carrier 2, or in… Figure 2 In the illustrated embodiment, the coverage of the light-transmitting layer 16, particularly on the first main surface 4, can be at least 70%, preferably at least 80%, more preferably at least 90%, and most preferably at least 95%, for example, complete coverage.

[0084] The first portion 8 of the LED filament light 8, 9 is light emitted from the front side 17 of the LED filament 100 and is light transmitted through the elongated package 6. Therefore, in this embodiment, it includes light transmitted through another portion of the light-transmitting layer 16 or light reflected by a portion of the light-transmitting layer 16.

[0085] The LED filament 100 also includes a back-side encapsulation 13. The back-side encapsulation 13 is arranged to cover at least a portion, particularly at least a major portion, of the light-transmitting layer 7 and the second main surface 5. The back-side encapsulation 13 is arranged on or adjacent to at least a portion of the second main surface 5 of the light-transmitting elongated carrier 2. The back-side encapsulation 13 does not contain any light-emitting material. The back-side encapsulation 13 may include a light-scattering material 15. More specifically, the back-side encapsulation 13 may include a concentration (e.g., measured as v / v%) of the light-scattering material 15 lower than the concentration of the light-emitting material present in the elongated encapsulation 6. The light-scattering material 15 may, for example, be BaSO4, TiO2, and Al2O3, or a combination thereof. The light-scattering material 15 is configured to scatter light passing through a portion of the light-transmitting layer 7.

[0086] The second portion 9 of the LED filament light 8, 9 is light emitted from the back side 18 of the LED filament 100, and therefore includes light transmitted through the back side encapsulation 13 in this embodiment.

[0087] The LED filament 100 also includes an additional elongated package 19. The additional elongated package 19 is disposed between the elongated package 6 and the light-transmitting elongated carrier 2. The additional elongated package 19 includes a non-emitting light-scattering material configured to scatter the LED light 10.

[0088] In another embodiment, a portion of the light-transmitting layer 16 may replace the reflective layer to prevent light loss from areas of the first main surface 4 not covered by the elongated encapsulation 6.

[0089] Now for reference Figure 3 and 4 This is to illustrate the effect of color point shifting or correction that can be obtained for the LED filament 1, 100 according to the present invention. Figure 3 The color spectrum of LED filament 1,100 according to the present invention is shown. Figure 4 It shows Figure 3 A close-up of the cross section IV of the color image.

[0090] Figure 3 The blackbody trajectory BBL is shown, and it is expected that the color points CP of LED filament light 8 and 9 emitted by LED filaments 1 and 100 will lie on this blackbody trajectory BBL. However, as Figure 4 As shown, it is possible that the color point CPI of the LED filament light 8 and 9 emitted by LED filament 1 and 100 deviates completely from the desired blackbody trajectory BBL. Figure 4Another color dot CP2 is also shown, located on or at least close enough to the BBL to meet desired requirements. Simulations have shown that, using the LED filament 1,100 according to the invention, since the LED filament 1,100 according to the invention includes a partially transparent layer 7 configured to provide non-uniform transmission of light, and particularly non-uniform transmission of light in the wavelength range of 400 nm to 800 nm, the color dot CP1 can be corrected or offset to obtain the position indicated by the color dot CP2. Therefore, using the LED filament 1,100 according to the invention, the color dots (such as color dot CPI) of the LED filament light 8,9 can be corrected or offset to obtain the desired target color dot.

[0091] at last, Figure 5 An exemplary lamp 20 is shown, comprising an LED filament 1 according to any embodiment of the present invention. In the illustrated embodiment, the LED filament 1 is a substantially straight LED filament. In other embodiments, the LED filament 1 of such a lamp may be an LED filament having other shapes, such as, but not limited to, spiral-shaped, helix-shaped, zigzag, twisted, flat, and combinations thereof.

[0092] The luminaire 20 also includes a driver or controller 25 configured to control the LEDs 3 of the LED filament 1. The controller 25 is configured to supply power to a plurality of LEDs 3 via circuitry of the LED filament 1 (not visible in the figure). The controller 25 may be further configured to control at least one of the CCT and CRI of the LED filament lights 8, 9. The controller 25 may also be configured to control other parameters related to the LEDs 3 and LED filament lights 8, 9.

[0093] The luminaire 20 also includes a sheath 21 that at least partially surrounds at least one LED filament 1. The luminaire 20 also includes a cap 22. Figure 5 As shown, the controller 25 is arranged within the housing 21. When the cap 22 is included, the controller 25 can also be arranged inside the cap 22, making it hidden and invisible. The luminaire 20 also includes threads 23 for connecting to a socket and terminals 24 for connecting to a power source.

[0094] The cover 21 of the luminaire 20 may also, and optionally, be provided with a coating (not shown) covering at least a portion of the cover 21, such as a reflective coating.

[0095] 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.

[0096] 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 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. An LED filament (1) configured to emit white LED filament light (8, 9) during operation, said LED filament comprising: The light-transmitting slender carrier (2) includes a first main surface (4) and a second main surface (5) opposite to the first main surface; An array of N LEDs (3) is configured to emit LED light (10) during operation and is arranged on the first main surface (4) of the light-transmitting elongated carrier (2). An elongated package (6) comprising a light-emitting material (12), the elongated package being arranged to cover at least a portion of the plurality of LEDs (3) and the first main surface (4), and the light-emitting material being configured to at least partially convert the LED light (10) into converted light (11); and Partially transparent layers (7; 16) are disposed on the light-transmitting elongated carrier (2), wherein the partially transparent layers (7; 16) are: - Configured to perform one or more of the reflection and absorption of at least a portion (14) of one or more of the LED light (10) and the converted light (11), and - It exhibits non-uniform transmission of light in the wavelength range from 400nm to 800nm. The LED light emitted by the array of the plurality of N LEDs (3) has a peak wavelength in a first wavelength range from 430 nm to 490 nm, wherein the converted light includes green-yellow light having a peak wavelength in a second wavelength range from 510 nm to 580 nm and red light having a peak wavelength in a third wavelength range from 600 nm to 680 nm; and wherein the partial light-transmitting layer (7; 16) has a first reflectivity (R1) in the first wavelength range, a second reflectivity (R2) in the second wavelength range and a third reflectivity (R3) in the third wavelength range, wherein the second reflectivity (R2) is higher than the first reflectivity (R1), and wherein the third reflectivity (R3) is higher than the first reflectivity (R1).

2. The LED filament according to claim 1, wherein the partial light-transmitting layer (7, 16) is disposed on one or both of the second main surface (5) of the elongated carrier (2) and the first main surface (4) of the elongated carrier (2).

3. The LED filament according to claim 1 or 2, wherein the partial light-transmitting layer (7; 16) is configured to reflect at least a portion (14) of one or more of the LED light (10) and the converted light (11), and wherein the partial light-transmitting layer (7; 16) is one or more of a reflective layer and a dichroic mirror, and wherein the partial light-transmitting layer (7; 16) is configured to correct the color point of the LED filament light (8, 9).

4. The LED filament according to any one of the preceding claims, wherein the first reflectivity (R1) is less than 20%, wherein R2-R1 ≥ 30%, and wherein R3-R1 ≥ 30%.

5. The LED filament according to claim 4, wherein 1.2 ≥ R2 / R3 ≥ 0.

8.

6. The LED filament according to any one of the preceding claims, wherein the LED filament light (8, 9) comprises a first portion (8) and a second portion (9), wherein the first portion (8) of the LED filament light is light emitted from the front side (17) of the LED filament (1), and wherein the second portion (9) of the LED filament light is light emitted from the back side (18) of the LED filament (1) and transmitted through the partial light-transmitting layer (7), and wherein the first portion (8) of the LED filament light is white light and the second portion (9) of the LED filament light is white light.

7. The filament of an LED according to any one of the preceding claims, wherein the LED filament light (8, 9) comprises a first portion (8) and a second portion (9), wherein the first portion (8) of the LED filament light is light emitted from the front side (17) of the LED filament (1), and wherein the second portion (9) of the LED filament light is LED filament light transmitted through the partial light-transmitting layer (7) and emitted from the back side (18) of the LED filament (1), and wherein one or both of the following are applicable: The luminous flux of the second portion (9) of the LED filament light is 0.2 to 0.6 times that of the first portion (8) of the LED filament light, and The first portion (8) of the LED filament light includes: The CCT of the second part (9) of the LED filament light is within 300K.

8. The LED filament according to any one of the preceding claims, wherein each of the array of the plurality of N LEDs emits light from (i) the top surface (31) of the LED and (ii) the side surface (32) of the LED and / or the bottom surface (33) of the LED.

9. The LED filament according to any one of the preceding claims, wherein the elongated package (6) comprises a non-emitting light-scattering material configured to scatter the light of the LED.

10. The LED filament according to any one of the preceding claims further comprises an additional elongated encapsulation (19) disposed between the elongated encapsulation (6) and the light-transmitting elongated carrier, the additional elongated encapsulation (19) comprising a non-emitting light-scattering material configured to scatter LED light.

11. The LED filament according to any one of the preceding claims further includes a back-side encapsulation (13) without light-emitting material, wherein the back-side encapsulation (13) is disposed on the second main surface (5) opposite to the first main surface (4) of the LED filament, and wherein the back-side encapsulation (13) is disposed to cover at least a major portion of the partial light-transmitting layer (7) and at least a portion of the second main surface (5).

12. The LED filament according to claim 11, wherein the back-side encapsulation (13) comprises a light-scattering material configured to scatter light transmitted through the partial light-transmitting layer (7).

13. The LED filament according to claim 12, wherein the concentration of the light-scattering material in the back-side encapsulation (13) is lower than the concentration of the light-emitting material in the elongated encapsulation (6).

14. An LED lamp or lighting device (20) comprising at least one LED filament (1) according to any one of the preceding claims.

Images