Stretchable LED lamp filament

Abstract

A stretchable LED filament (1) configured to provide LED filament light in operation, the stretchable LED filament (1) comprising: an elongate carrier (2) comprising a longitudinal direction (L), a transverse direction (T), a first major surface (21), a second major surface (22), a first longitudinal edge (23) and a second longitudinal edge (24), the first and second longitudinal edges (23 and 24) are opposite edges connecting the first and second major surfaces (21 and 22); a plurality of LEDs (3) configured to provide LED light in operation and arranged on the first main surface (21); an elongated package (4) encapsulating the plurality of LEDs (3) and covering at least a portion of the first main surface (21), the elongated carrier (2) being flexible and comprising a tortuous shape, the elongated package (4) being flexible, the first longitudinal edge (23) comprising a first recess (25) and the second longitudinal edge (24) comprising a second recess (26), the first recess (25) being substantially substantially rectangular, and the second recess (26) being substantially rectangular. Wherein each of the first recesses (25) comprises a first extension (27) in the longitudinal direction (L) and each of the second recesses (26) comprises a second extension (28) in the longitudinal direction (L) and are arranged such that the first extension (27) of each first recess (25) forms an overlap (29) with the second extension (28) of at least one directly opposite second recess (26).

Description

Technical Field

[0001] This invention relates to a stretchable LED filament configured to provide LED filament light during operation. The stretchable LED filament comprises: an elongated carrier including a longitudinal direction, a transverse direction extending perpendicular to the longitudinal direction, a height direction extending perpendicular to both the transverse and longitudinal directions, a first main surface, a second main surface, a first longitudinal edge, and a second longitudinal edge, the first and second longitudinal edges being opposing longitudinal edges connecting the first and second main surfaces; a plurality of LEDs configured to provide LED light during operation and arranged on the first main surface of the elongated carrier; and an elongated encapsulation that encapsulates the plurality of LEDs and covers at least a portion of the first main surface. The invention also relates to luminaires and lamps including such a stretchable LED filament. Background Technology

[0002] The lighting trend is towards LED filament lamps. An LED filament lamp is an LED lamp designed to resemble a traditional incandescent bulb, featuring a visible filament for aesthetic and light distribution purposes, but with the high efficiency of a light-emitting diode. The latest trend in LED filament lamps is to incorporate LED filaments within the luminaire.

[0003] CN 205447297 U discloses a stretchable LED filament. The LED filament includes a metal substrate and a plurality of LEDs. The metal substrate includes an upper connecting portion and a lower connecting portion. The LEDs are connected to the upper connecting portion and the lower connecting portion. A Z-shaped metal connecting member is arranged between the upper connecting portion and the lower connecting portion. In other words, a spring-like member is inserted between the upper connecting portion and the lower connecting portion. The light-emitting surface of the LED may also be coated with phosphor.

[0004] The goal is to improve the performance, functionality, and / or appearance of LED filaments. Summary of the Invention

[0005] One object of the present invention is to overcome this problem and to provide a stretchable LED filament with improved performance, functionality and / or appearance.

[0006] According to a first aspect of the invention, this and other objectives are achieved by a stretchable LED filament configured to provide LED filament light in operation, the stretchable LED filament comprising:

[0007] ■ An elongated carrier, comprising a longitudinal direction, a transverse direction extending perpendicular to the longitudinal direction, a height direction extending perpendicular to both the transverse and longitudinal directions, a first main surface, a second main surface, a first longitudinal edge, and a second longitudinal edge, wherein the first longitudinal edge and the second longitudinal edge are opposing longitudinal edges connecting the first main surface and the second main surface.

[0008] ■ Multiple LEDs, configured to provide LED light during operation, are arranged on the first main surface of the elongated carrier, and

[0009] ■ An elongated package that encapsulates the plurality of LEDs and covers at least a portion of the first main surface.

[0010] The elongated carrier is flexible and includes a zigzag shape with a bend pointing laterally. The elongated package is flexible. The first longitudinal edge includes a first recess and the second longitudinal edge includes a second recess. Each of the first recesses includes a first extension in the longitudinal direction and each of the second recesses includes a second extension in the longitudinal direction. The first and second recesses are arranged such that the first extension of each first recess overlaps with the second extension of at least one directly opposite second recess. The LED filament includes a first length L1 in an unstretched configuration, which is achieved when no external force is applied to the LED filament. The LED filament includes a second length L2 in a stretched configuration, which is achieved when a tensile force is applied to the LED filament. The second length is greater than the first length.

[0011] Thus, and particularly since the first longitudinal edge includes a first recess and the second longitudinal edge includes a second recess, wherein each of the first recesses includes a first extension in the longitudinal direction and each of the second recesses includes a second extension in the longitudinal direction and is arranged such that the first extension of each first recess overlaps with the second extension of at least one directly opposite second recess, an LED filament is provided in which at least one of performance, functionality and appearance is improved in the LED filament in its unstretched state and in its stretched state.

[0012] Furthermore, since the elongated carrier is flexible and includes a tortuous shape with a bend pointing laterally, and given that the elongated package is flexible, an improved LED filament is provided, which has a simpler and more durable configuration and can, in principle, be fixed in any tensile state.

[0013] The elongated encapsulation can be made of silicone. Practical use has shown that silicone is a particularly useful material for stretchable LED filaments because it is both flexible and stretchable, and also resistant to abrasion caused by LED light emitted from multiple LEDs.

[0014] Stretchable LED filaments may include a maximum stretch percentage MS, defined as MS = (L2 / L1-1)∙100%, and MS ranges from 3% to 30%. MS depends on the design / configuration of the elongated carrier (its tortuous shape). The required MS depends on the lighting application. In embodiments, MS may be at least 3% to obtain a reliable LED filament, as LED filaments with no (or very low) stretch characteristics / properties have reduced reliability, especially if the LED filament is positioned between two points (on which forces are applied). In embodiments, MS may be at most 30% to obtain a reliable LED filament, as LED filaments with excessive stretch characteristics / properties have reduced reliability. Other ranges are also acceptable depending on the filament's flexibility and / or reliability, for example, 3% to 10% for filaments of lower flexibility / reliability and 3% to 50% for filaments of higher flexibility / reliability.

[0015] On the one hand, some stretchability is certainly needed to allow the LED filament to be stretched. On the other hand, the stretchability should not be too great, as this would compromise the improved appearance and lighting effect of the LED filament. Furthermore, the required amount of stretchability is related to the application of the stretchable LED filament. For example, if a long, stretchable LED filament is to be suspended between two points, a certain amount of stretchability is needed to keep the stretchable LED filament straight, especially over time. Given these considerations, a lower limit of 2% and an upper limit of 20% have been found to be particularly suitable.

[0016] LED filaments can be elastic. Therefore, after being stretched, when the force is removed, the LED filament will return to its original shape. In the case of inelasticity, after being stretched, when the force is removed, the LED filament will remain in the stretched configuration.

[0017] When the stretchable LED filament is in the unstretched configuration, and optionally when the stretchable LED filament is in the stretched configuration, the plurality of LEDs can be arranged in a zigzag pattern, and at least five LEDs can be arranged in the section of the elongated carrier corresponding to the first extension and at least five LEDs can be arranged in the section of the elongated carrier corresponding to the second extension.

[0018] More generally, the pitch of LEDs in a plurality of LEDs, or the gap between LEDs, can be selected to be a turn pitch that is significantly smaller than the zigzag shape of the elongated carrier.

[0019] Therefore, high-quality LED filament light and the simulation of the filament's particularly good function were achieved.

[0020] The stretchable LED filament may also include circuitry for supplying power to multiple LEDs, wherein the circuitry is arranged in a zigzag pattern.

[0021] Thus, in particular, by providing the circuit with the aforementioned meandering pattern, short circuits are prevented and a stable electrical connection is achieved.

[0022] The LEDs in a plurality of LEDs can be arranged such that the gap between the LEDs is equal to or less than 0.5 mm, preferably equal to or less than 0.3 mm, more preferably equal to or less than 0.2 mm, and most preferably equal to or less than 0.1 mm.

[0023] Slender carriers can be continuous.

[0024] Therefore, the appearance of the LED filament is improved, especially in both the unstretched and stretched states.

[0025] Slender carriers can be made of polymers.

[0026] Due to the combination of flexibility and strength of this material, polymers are suitable for use as carriers.

[0027] The zigzag shape of an elongated carrier may include a sinusoidal pattern or may not have sharp cuts.

[0028] Therefore, the appearance and performance of LED filaments are improved, especially in both unstretched and stretched states.

[0029] The elongated carrier includes a width W, and the first recess and the second recess each include a width WR, wherein WR may be greater than 0.5W, or WR may be less than or equal to 0.7W.

[0030] Therefore, LED filaments become particularly stretchable.

[0031] The slender carrier has a tortuous shape with a tortuous width WM, and the first and second recesses each have a length LR, and LR can be greater than 0.5WM.

[0032] This ensures that each recess extends further than the width of the bend, which in turn ensures that the LED filament is optimally stretchable.

[0033] The elongated package may also cover at least a portion of the first recess and at least a portion of the second recess. Alternatively or additionally, the elongated package may be straight.

[0034] Thus, a stretchable LED filament with improved stretchability is obtained.

[0035] The portion of the elongated package covering the recess can be more flexible than the rest of the elongated package. Alternatively or additionally, as measured in the height direction of the LED filament, the portion of the elongated package covering the recess can be thinner than the rest of the elongated package. Alternatively or additionally, the portion of the elongated package covering the recess can be made of a material softer than the material used to make the rest of the elongated package.

[0036] Each of these embodiments ensures the acquisition of a stretchable LED filament with improved stretchability.

[0037] The stretchable LED filament may also include an additional elongated package that is flexible and covers at least a portion of the second main surface, wherein the additional elongated package is in physical contact with the elongated package.

[0038] Thus, a stretchable LED filament with improved stretchability is obtained.

[0039] Multiple LEDs can be configured to provide blue LED light during operation, and the elongated package can include a light-emitting material configured to at least partially convert the LED light into converted light. Alternatively, or additionally, the elongated package can include a light-scattering material configured to at least partially scatter the LED light into diffused light.

[0040] Each of these embodiments provides a stretchable LED filament that includes improved LED filament light or illumination effects and an improved ability to convincingly mimic the filament.

[0041] The luminescent material can be a greenish-yellow or red phosphor. This phosphor is particularly suitable for use in combination with LEDs that provide blue LED light.

[0042] The stretchable LED filament may also include two mechanical connectors attached to the LED filament at opposite ends, and configured to secure the LED filament in a stretched configuration.

[0043] Therefore, a stretchable LED filament is provided, which can be fixed in its stretched state in a particularly simple manner, and which can be attached to, for example, a luminaire or lamp in a particularly simple manner.

[0044] The stretchable LED filament may also include two electrical connectors, wherein the two mechanical connectors are arranged adjacent to the two electrical connectors. Alternatively or additionally, the stretchable LED filament may also include two electrical connectors, wherein the two mechanical connectors include the two electrical connectors.

[0045] Each of these two embodiments provides a stretchable LED filament that can be fixed in its stretched state in a particularly simple manner, and which is particularly easy to attach to, for example, a luminaire or lamp. In the latter case, the stretchable LED filament also has a particularly simple structure.

[0046] In the unstretched configuration, the LED filament can provide LED filament light with a first intensity I1 and a first correlated color temperature CCT1, and in the stretched configuration, the LED filament can provide LED filament light with a second intensity I2 and a second correlated color temperature CCT2, wherein I1 ≠ I2, preferably wherein I1 > I2, and / or wherein CCT1 ≠ CCT2, preferably wherein CCT2 > CCT1. In an embodiment, |CCT2 - CCT1| ≥ 300K or |CCT2 - CCT1| ≥ 500K.

[0047] This provides an LED filament comprising at least two different appearances depending on the state of the LED filament (stretched or unstretched), the intensity of the emitted light, and / or the associated color temperature.

[0048] The present invention also relates to LED lamps or luminaires comprising stretchable LED filaments according to the present invention.

[0049] In an embodiment, the LED filament light can be white light, for example, having a correlated color temperature in the range of 1700K to 6500K and / or a CRI of at least 80. The LED lamp or luminaire may also include at least two attachment points, and the stretchable LED filament may include at least two mechanical connectors attached to opposite ends of the stretchable LED filament, and these mechanical connectors are configured to be attached to the at least two attachment points in a stretched state of the stretchable LED filament.

[0050] This configuration is particularly reliable when the filament heats up due to the heat generated when the LED emits light. It also helps maintain the straightness of the stretchable LED filament, for example, during use or throughout its lifespan. The latter is especially suitable for long stretchable LED filaments, such as those longer than 10cm or 20cm in their unstretched state.

[0051] The LED lamp or luminaire may include at least two attachment points, which are arranged such that the stretchable LED filament can be secured in the maximum stretch state.

[0052] The LED lamp or luminaire may also include one or more intermediate attachment points arranged between the end attachment points, thereby enabling the stretchable LED filament to be secured in a stretched state, wherein the stretch of the stretchable LED filament is less than the stretch in the maximum stretched state.

[0053] Therefore, stretchable LED filaments can be attached to luminaires or lamps in any desired stretch state.

[0054] It should be noted that the present invention relates to all possible combinations of the features described in the claims. Attached Figure Description

[0055] 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.

[0056] Figure 1 A top view of an embodiment of a stretchable LED filament according to the present invention in its unstretched state is shown.

[0057] Figure 2 It shows that according to Figure 1 A top view of a stretchable LED filament, including the encapsulation, for simplicity... Figure 1 Not shown in the image.

[0058] Figure 3 It shows that according to Figure 2 A bottom view of a stretchable LED filament.

[0059] Figure 4 The figure shows the condition under tension. Figure 1 A top view of a stretchable LED filament.

[0060] Figure 5 A schematic side view of a luminaire including an LED filament according to the present invention is shown.

[0061] 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

[0062] 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.

[0063] As used herein, the term “unstretched state” in relation to a given feature or element (e.g., the LED filament 1 according to the invention) is intended to indicate a state in which no tensile force is applied to the given feature or element.

[0064] As used herein, the term "tension state" in relation to a given feature or element (e.g., the LED filament 1 according to the invention) is intended to indicate a state in which a tensile force is applied to said given feature or element. The term "tension state" is intended to be used regardless of the magnitude of the applied tensile force.

[0065] As used herein, the terms “fully stretched” and “maximum stretched” for a given feature or element (e.g., an LED filament 1 according to the invention) are intended to indicate a state in which a tensile force is applied to the given feature or element such that any additional tensile force applied would cause plastic deformation of the given feature or element.

[0066] First refer to Figures 1 to 4 This illustrates a stretchable LED filament 1 according to the present invention. More specifically, Figure 1 and Figure 2 Top views of an embodiment of the stretchable LED filament 1 according to the present invention are shown in its unstretched state and with and without the encapsulation 4. Figure 3 A bottom view of the stretchable LED filament 1 is shown, and Figure 4 A top view of the stretchable LED filament 1 in the stretched state is shown.

[0067] Typically, and regardless of the embodiment, the stretchable LED filament 1 includes an elongated carrier 2, a plurality of LEDs 3, and an elongated package 4. The stretchable LED filament 1 is configured to provide LED filament light during operation.

[0068] The slender carrier 2 is flexible, thus enabling the stretchable LED filament 1 to... Figure 1 and Figure 2 The unstretched state shown and as Figure 4 The stretching is shown between the stretched states, particularly in the longitudinal direction L of the elongated carrier 2. When no external force is applied to the LED filament 1, the LED filament 1 is in an unstretched configuration. When a tensile force is applied to the LED filament 1, the LED filament is in a stretched configuration. The LED filament 1 in the unstretched configuration includes a first length L1. The LED filament 1 includes a second length L2 in the stretched configuration. The second length L2 depends on the magnitude of the tensile force applied to the LED filament 1. Typically, L2 is greater than L1. The stretchable LED filament 1 includes a maximum stretch percentage MS. The maximum stretch percentage MS is defined as MS = (L2 / L1 - 1)∙100%. The maximum stretch percentage MS can range from 3% to 30%.

[0069] The LED filament 1 can be configured, for example, to provide LED filament light with a first intensity I1 and a first correlated color temperature CCT1 in an unstretched configuration, and to provide LED filament light with a second intensity I2 and a second correlated color temperature CCT2 in a stretched configuration. The first intensity I1 may be different from or greater than the second intensity I2. The first correlated color temperature CCT1 may be different from or greater than the second correlated color temperature CCT2. The LED filament can also be configured to provide LED filament light with a second intensity I2 and a second correlated color temperature CCT2 in a stretched configuration, wherein the second intensity I2 and the second correlated color temperature CCT2 depend on the magnitude of the stretching force applied to the stretchable LED filament 1.

[0070] The elongated carrier 2 includes a zigzag shape. The zigzag shape may have a sinusoidal pattern. The zigzag shape may not have sharp cuts. Alternatively, or additionally, the zigzag shape may have a square pattern, a triangular pattern, and / or a serrated pattern. The elongated carrier 2 may be continuous, i.e., monolithic. The elongated carrier 2 may be made of a suitable polymer. The zigzag shape of the elongated carrier 2 includes a zigzag width WM, and the first recess 25 and the second recess 26 each include a length LR. The length LR may be greater than 0.5 times the zigzag width WM.

[0071] The elongated carrier 2 includes a longitudinal direction L, a transverse direction T, and a height direction H. The transverse direction T and the longitudinal direction L are perpendicular to each other and extend in the same plane. The height direction H extends perpendicular to both the transverse direction T and the longitudinal direction L. The elongated carrier 2 also includes a first main surface 21, a second main surface 22, a first longitudinal edge 23, and a second longitudinal edge 24. The first main surface 21 and the second main surface 22 are surfaces opposite to each other. The first longitudinal edge 23 and the second longitudinal edge 24 are longitudinal edges opposite to each other. The first longitudinal edge 23 and the second longitudinal edge 24 connect the first main surface 21 and the second main surface 22.

[0072] The first longitudinal edge 23 includes one or more first recesses 25. The second longitudinal edge 24 includes one or more second recesses 26. Each first recess 25 and each second recess 26 includes a length LR measured in the longitudinal direction L. Each first recess 25 includes a first extension 27 in the longitudinal direction L. Each second recess 26 includes a second extension 28 in the longitudinal direction L. The first extension 27 of each first recess 25 forms an overlap 29 with the second extension 28 of at least one directly opposite second recess 26, such as... Figure 1 The shaded area is shown in the image. Figure 1In the illustrated embodiment, the size of the overlapping portion 29 is approximately half the length LR of the recesses 25 and 26. In other embodiments, the overlapping portion may be less than half the length LR of the recesses 25 and 26, such that, for example, it is one-quarter of the length LR of the recesses 25 and 26, or 0.1 LR.

[0073] The elongated carrier 2 also includes a width W. The width W is measured as the shortest distance between the first and second longitudinal edges 23 and 24, or in other words, the distance between the first and second longitudinal edges 23 and 24, as measured in the transverse direction T of the elongated carrier 2. The first recess 25 and the second recess 26 each have a width WR. The dimensions of the width W of the elongated carrier and the width WR of the corresponding recesses 25 and 26 can be selected such that WR > 0.5W or WR ≤ 0.7W.

[0074] Multiple LEDs 3 are configured to provide LED light during operation. The multiple LEDs 3 can, for example, be configured to provide LED light with a blue tint during operation. The multiple LEDs 3 are arranged on a first main surface 21 of an elongated carrier 2. The multiple LEDs 3 can be attached to the elongated carrier 2 in an unstretched configuration of the stretchable LED filament 1. The multiple LEDs 3 can be arranged in a zigzag pattern, at least in the unstretched configuration of the stretchable LED filament 1, but optionally also in the stretched configuration of the stretchable LED filament 1. At least five, eight, or ten LEDs can be arranged within a section of the elongated carrier 2 corresponding to the first extension 27 of the first recess 25. Similarly, at least five, eight, or ten LEDs can be arranged within a section of the elongated carrier 2 corresponding to the second extension 28 of the second recess 26.

[0075] Multiple LEDs 3 are arranged on an elongated carrier 2 with a pitch 31. The pitch 31 can be defined as the center-to-center distance between two adjacent LEDs of the multiple LEDs 3. Typically, the pitch 31 can be selected to be smaller than or even smaller than the pitch of LEDs in conventional prior art LED strips. The pitch 31 can be less than 0.5 mm, equal to or less than 0.3 mm, equal to or less than 0.2 mm, or even equal to or less than 0.1 mm.

[0076] An elongated package 4 is arranged to encapsulate a plurality of LEDs 3. The elongated package 4 also covers at least a portion of the first main surface 21 of the elongated carrier. The elongated package 4 is flexible. For example, the elongated package 4 can be made of silicone, particularly optical grade silicone. The elongated package 4 can be straight. The elongated package 4 may also cover a first recess 25 or a second recess 26, or both the first and second recesses 25 and 26. Figure 2The diagram shows a portion 41 of an elongated package 4 that bridges or covers a first recess 25 or a second recess 26, or both of the first and second recesses 25 and 26. The portion 41 may be more flexible than the remainder of the elongated package 4. Alternatively or additionally, the portion 41 may be thinner or have a smaller thickness than the remainder of the elongated package 4, wherein this thickness is measured in the height direction H of the stretchable LED filament 1. Alternatively or additionally, the portion 41 may be made of a material softer than the material used to make the remainder of the elongated package 4.

[0077] The elongated package 4 may include a light-emitting material configured to at least partially convert LED light into converted light. The light-emitting material may, for example, be a green-yellow phosphor or a red phosphor. Alternatively or additionally, the elongated package 4 may include a light-scattering material configured to at least partially scatter LED light to produce scattered light.

[0078] See details Figure 3 The stretchable LED filament 1 may also include a circuit 5 for supplying electrical power to a plurality of LEDs 3. The circuit 5 may be arranged on an elongated carrier 2. The circuit 5 may be arranged in a zigzag pattern. The circuit 5 may include one or more electrical tracks or lines.

[0079] The stretchable LED filament 1 may also include two mechanical connectors 8 (see Figure 2 and Figure 4 These two mechanical connectors 8 are attached to the stretchable LED filament 1, specifically at opposite ends 11 and 12 of the stretchable LED filament 1. The two mechanical connectors 8 can be attached to the elongated carrier 2, or to the package 4, or both. The two mechanical connectors 8 are configured to secure the stretchable LED filament 1 in its stretched state. In principle, more than two electrical connectors 8 can be provided. For example, as... Figure 5 As schematically shown, the stretchable LED filament 1 may include four mechanical connectors 8, 8', namely one mechanical connector 8 at each of the opposite ends 11 and 12, and two intermediately arranged mechanical connectors 8'. The mechanical connectors 8, 8' can, in principle, be attached to the stretchable LED filament 1 at a location other than the opposite ends 11 and 12, to allow the stretchable LED filament 1 to be secured in one or more intermediate and partially stretched states.

[0080] The stretchable LED filament 1 may also include two electrical connectors 7. The two electrical connectors 7 are configured to connect multiple LEDs 3 and / or circuits 5 to an electrical power source, such as mains power. The two mechanical connectors 8 and the two electrical connectors 7 may be arranged in pairs, adjacent to each other. Alternatively, the two mechanical connectors 8 and the two electrical connectors 7 may be integrated in pairs into the same connector.

[0081] The stretchable LED filament 1 may also optionally include an additional elongated encapsulation 6 – see Figure 3 The additional elongated package 6 can be flexible. The additional elongated package 6 can be made of a flexible material, such as, for example, silicone. The additional elongated package 6 is arranged to cover at least a portion of the second main surface 22. The additional elongated package 6 is in physical contact with the elongated package 4 along at least a portion of the stretchable LED filament 1.

[0082] The additional elongated package 6 can be straight. The additional elongated package 6 can also cover the first recess 25 or the second recess 26, or both the first and second recesses 25 and 26. Figure 3 The diagram shows a portion 61 of an additional elongated package 6 that bridges or covers the first recess 25 or the second recess 26, or both the first and second recesses 25 and 26. The portion 61 may be more flexible than the remainder of the additional elongated package 6. Alternatively or additionally, the portion 61 may be thinner or have a smaller thickness than the remainder of the additional elongated package 6, wherein this thickness is measured in the height direction H of the stretchable LED filament 1. Alternatively or additionally, the portion 61 may be made of a material softer than the material used to manufacture the remainder of the additional elongated package 6.

[0083] Turn now Figure 5 A schematic side view of a luminaire 50 including a stretchable LED filament 1 according to the present invention is shown.

[0084] The luminaire 50 may include an electrical connector 56 and a terminal 57 for connecting the stretchable LED filament 1 to an electrical energy source such as mains power.

[0085] The luminaire 50 may include a driver or controller 58 configured to control a plurality of LEDs 3 of the stretchable LED filament 1. The controller 58 is configured to power the plurality of LEDs 3 via the circuitry 5 of the stretchable LED filament 1 and the electrical connection 56 of the luminaire 50. The controller 58 may also be configured to control at least one of the CCT and CRI of the LED filament lamp. The controller 58 may also be configured to control other parameters related to the plurality of LEDs 3, the stretchable LED filament 1, and the LED filament lamp.

[0086] The luminaire 50 also includes a housing 51 that at least partially encloses the at least one stretchable LED filament 1. The luminaire 50 also includes a cap 52. Figure 5 As shown, the controller 58 is arranged inside the cap 52, thus concealing it from view. When the cap 52 is not included, the controller 58 may also be arranged within the housing 51. The luminaire 50 may also include threads 53 for connection to a socket.

[0087] The housing 51 of the luminaire 50 may also, and optionally, be provided with a coating, such as a reflective coating, covering at least a portion of the housing.

[0088] The luminaire 50 also includes at least two end attachment points 54. Two mechanical connectors 8 disposed on the stretchable LED filament 1 are configured to be attached to the at least two end attachment points 54 in the fully stretched state of the stretchable LED filament 1.

[0089] The luminaire 50 may also include at least one (two in the illustrated embodiment) intermediate attachment point 55. Multiple intermediate attachment points 55 are arranged between at least two attachment points 54. Two intermediate mechanical connectors 8' disposed on the stretchable LED filament 1 are configured to be attached to one or more intermediate attachment points 55 in a stretched state (not necessarily a fully stretched state) of the stretchable LED filament 1.

[0090] Those skilled in the art will recognize that the present invention is by no means limited to the foregoing preferred embodiments. Rather, many modifications and variations are possible within the scope of the appended claims.

[0091] 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. A stretchable LED filament (1) configured to provide LED filament light during operation, the stretchable LED filament comprising: The elongated carrier (2) includes a longitudinal direction (L), a transverse direction (T) extending perpendicular to the longitudinal direction, a height direction (H) extending perpendicular to both the transverse and longitudinal directions, a first main surface (21), a second main surface (22), a first longitudinal edge (23) and a second longitudinal edge (24), wherein the first longitudinal edge and the second longitudinal edge are longitudinal edges opposite to each other connecting the first main surface and the second main surface; Multiple LEDs (3) are configured to provide LED light during operation and are arranged on the first main surface (21) of the elongated carrier; as well as An elongated package (4) encapsulates the plurality of LEDs (3) and covers at least a portion of the first main surface (21); The elongated carrier (2) is flexible and includes a zigzag shape with a bend pointing in the lateral direction (T). The elongated package (4) is flexible. The first longitudinal edge (23) includes a first recess (25) and the second longitudinal edge (24) includes a second recess (26). Each of the first recesses (25) includes a first extension (27) in the longitudinal direction and each of the second recesses (26) includes a second extension (28) in the longitudinal direction, and wherein each of the first recesses (25) and each of the second recesses (26) are arranged such that the first extension of each first recess overlaps with the second extension of at least one directly opposite second recess (29). and The LED filament (1) has a first length (L1) in an unstretched configuration, which is achieved when no external force is applied to the LED filament, and a second length (L2) in a stretched configuration, which is achieved when a tensile force is applied to the LED filament, wherein L2 > L1. The stretchable LED filament (1) includes a maximum stretch percentage (MS), wherein the maximum stretch percentage is defined as MS = (L2 / L1-1)∙100%, and wherein MS is in the range of 3% to 30%.

2. The stretchable LED filament according to claim 1, wherein, In the unstretched configuration of the LED filament (1) and optionally also in the stretched configuration, the plurality of LEDs (3) are arranged in a zigzag pattern, wherein at least five LEDs are arranged in the section of the elongated carrier (2) corresponding to the first extension (27), and wherein at least five LEDs are arranged in the section of the elongated carrier (2) corresponding to the second extension (28).

3. The stretchable LED filament according to any one of the preceding claims, and further comprising a circuit (5) for supplying electrical energy to the plurality of LEDs (3), wherein the circuit (5) is arranged in a zigzag pattern.

4. The stretchable LED filament according to any one of the preceding claims, wherein the zigzag shape of the elongated carrier (2) comprises a sinusoidal pattern or has no sharp cuts.

5. The stretchable LED filament according to any one of the preceding claims, wherein the tortuous shape of the elongated carrier has a tortuous width (WM), wherein the first recess (25) and the second recess (26) each include a length (LR), wherein LR > 0.5∙WM.

6. The stretchable LED filament according to any one of the preceding claims, wherein one or more of the following are applicable: The elongated package (4) also covers at least a portion of the first recess (25) and at least a portion of the second recess (26), and / or The elongated package (4) is straight.

7. The stretchable LED filament according to claim 6, wherein one or more of the following are applicable: The portion (41) of the elongated package (4) that covers the recess is more flexible than the rest of the elongated package, and / or As measured in the height direction (H) of the LED filament (1), the portion (41) of the elongated package (4) covering the recess is thinner than the rest of the elongated package, and / or The portion (41) of the elongated package (4) that covers the recess is made of a softer material than the material used to make the rest of the elongated package.

8. The stretchable LED filament according to any one of the preceding claims further includes an additional elongated encapsulation (6), said additional elongated encapsulation being flexible and covering at least a portion of the second main surface (22), wherein said additional elongated encapsulation (6) is in physical contact with said elongated encapsulation (4).

9. The stretchable LED filament according to any one of the preceding claims, wherein one or more of the following are applicable: (i) The plurality of LEDs (3) are configured to provide LED light with blue color during operation, and the elongated package (4) includes a light-emitting material configured to at least partially convert the LED light into converted light, and (ii) The elongated package (4) includes a light-scattering material configured to at least partially scatter the LED light into scattered light.

10. The stretchable LED filament according to any one of the preceding claims, further comprising two mechanical connectors (8) attached to the LED filament at opposite ends (11, 12) of the LED filament, and the two mechanical connectors (8) configured to secure the LED filament (1) in the stretch configuration of the LED filament.

11. The stretchable LED filament of claim 10, further comprising two electrical connectors (7), wherein the two mechanical connectors (8) are arranged adjacent to the two electrical connectors (7), or wherein the two mechanical connectors (8) comprise the two electrical connectors (7).

12. The stretchable LED filament according to any one of the preceding claims, wherein the LED filament is configured to provide LED filament light having a first intensity (I1) and a first correlated color temperature (CCT1) in the unstretched configuration, wherein the LED filament is configured to provide LED filament light having a second intensity (I2) and a second correlated color temperature (CCT2) in the stretched configuration, and wherein I1 ≠ I2, and / or wherein CCT1 ≠ CCT2.

13. An LED lamp or luminaire (50) comprising an LED filament (1) according to any one of the preceding claims.

14. The LED lamp or luminaire according to claim 13, wherein the LED lamp or luminaire (50) further comprises at least two attachment points (54), and wherein the LED filament (1) comprises at least two mechanical connectors (8) attached to the LED filament at opposite ends (11, 12) of the LED filament, and the two mechanical connectors (8) are configured to be attached to the at least two attachment points (54) in a stretched state of the LED filament (1).

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