Light emitting diode filament configuration with at least one bending unit - Patents.com

Abstract

The present disclosure relates to a light emitting diode (LED) filament configuration 100, the filament configuration comprising an elongated, flexible LED filament 110 having a plurality of LEDs arranged along an elongate portion of the filament. The configuration further comprises a bending unit 120 having a body with a channel 121 formed therein. A portion of the LED filament is disposed within the channel of the bending unit, the bending unit being at least partially curved and adapted to impart a bend to the LED filament.

Description

[Technical field]

[0001] The present disclosure relates generally to the field of solid state lighting, and more particularly to a light emitting diode (LED) filament arrangement comprising a bending unit for creating a bend in the LED filament. [Background technology]

[0002] Incandescent lamps are being rapidly replaced by light-emitting diode (LED)-based lighting solutions. Nevertheless, the appearance and aesthetics offered by incandescent light bulbs are preferred by consumers who also appreciate the opportunity to use retrofit LED lamps in existing lighting fixtures. Thus, the goal of LED-based lighting developers is to provide decorative retrofit LED lamps that provide aesthetically pleasing appearance and lighting.

[0003] To provide sufficient illumination from an LED lamp, several short LED filaments may be used, but this can be complicated to manufacture, as each LED filament needs to be individually electrically connected.

[0004] Another option is to use a longer flexible filament that can be bent to create various configurations, however, such a solution may exhibit erratic behavior as the bent or stressed LED filament portion may be susceptible to reliability issues. Summary of the Invention [Problem to be solved by the invention]

[0005] It is therefore an object of the present invention to overcome at least some of the above-mentioned drawbacks. This and other objects are achieved by an LED filament arrangement as defined in the accompanying independent claims. Further embodiments are defined by the dependent claims. [Means for solving the problem]

[0006] According to an aspect of the disclosure, a light emitting diode (LED) filament configuration is provided. The LED filament configuration comprises an elongated flexible LED filament having a plurality of LEDs arranged along an elongation (i.e., along a direction of elongation) of the LED filament. The configuration further comprises a bending unit having a body, the body having an at least partially curved channel formed therein. A portion of the LED filament is disposed within the channel of the bending unit. The bending unit is adapted to induce a bend in the LED filament.

[0007] It will be understood that no further portion of the LED filament is disposed within the bending unit. Providing a bending unit to induce a bend in the LED filament may improve the reliability of the LED filament configuration. For example, an LED filament configuration using a bending unit to induce a bend in the LED filament may better retain the initial (intended) shape of the LED filament. Furthermore, the bending unit may hold the LED filament in a bent configuration such that the LED filament is not straightened or bent too much. In an LED filament that is bent too much or bent too many times, the electrical connection between the LEDs may be damaged, for example. Furthermore, many LED filaments include a substrate on which the LEDs are disposed, and an encapsulant covers the LEDs and at least one side of the substrate. Excessive bending or excessive bending of such an LED filament may cause the encapsulant of the LED filament to peel off from the substrate and / or the LED, resulting in a less uniform light distribution. It will be understood that the bending unit may be pre-formed to induce a desired bend / or orientation in the flexible LED filament. In this way, a desired decorative appearance can be obtained. Furthermore, light distribution can be enhanced, since a more optimal configuration and orientation of the LED filaments can be obtained and maintained. The bending unit may have a length in the range of 5 to 50 mm. In particular, the bending unit may have a length in the range of 8 to 30 mm. More particularly, the bending unit may have a length in the range of 10 to 20 mm.

[0008] Alternatively, the length of the bending unit may be defined relative to the length of the LED filament. For example, the length of the bending unit may be 0.05 to 0.3 times the length of the LED filament. Specifically, the length of the bending unit may be 0.08 to 0.25 times the length of the LED filament. More specifically, the length of the bending unit may be within a range of 0.1 to 0.2 times the length of the LED filament.

[0009] The bending unit may further have an inner diameter, i.e., a diameter of the channel. For example, the bending unit may have an inner diameter (i.e., a diameter of the channel) in the range of 1 to 10 mm. Specifically, the bending unit may have an inner diameter in the range of 2 to 7 mm. More specifically, the bending unit may have an inner diameter in the range of 3 to 5 mm.

[0010] Alternatively, the inner diameter of the bending unit may be defined relative to the diameter of the LED filament. For example, the inner diameter of the bending unit may be 0.8 to 1.5 times the diameter of the LED filament. Specifically, the inner diameter of the bending unit may be 0.9 to 1.3 times the diameter of the LED filament. More specifically, the inner diameter of the bending unit may be 1 to 1.2 times the diameter of the LED filament.

[0011] According to some embodiments, the flexion unit may be at least partially optically transparent.

[0012] For example, the body of the bending unit may be translucent or transparent. Such an embodiment may provide improved light distribution (or increased illumination) since the light emitted by the portion of the LED filament disposed within the channel is not blocked.

[0013] Such an at least partially optically transmissive flexion unit may comprise a material such as glass or a polymer.

[0014] According to some embodiments, the flexion unit may be at least partially light-tight.

[0015] A configuration with such a bending unit may give the illusion or appearance that multiple shorter LED filaments are being used.

[0016] The at least partially light-tight flexion unit may comprise a material such as copper or aluminum.

[0017] According to some embodiments, the flexion unit is rated at 200 Wm -1 K -1 The material may include a material having a thermal conductivity of equal to or greater than 100 .mu.m.

[0018] Such embodiments may provide improved thermal management, for example by improving the transfer of heat generated by the portion of the LED filament disposed within the channel, thereby maintaining the LED filament at a suitable temperature.

[0019] Specifically, the main unit must be at least 250Wm -1 K -1 More specifically, the body may include a material having a thermal conductivity of at least 350 Wm -1 K -1 For example, the body may comprise a highly thermally conductive material such as aluminum, iron, steel, or copper.

[0020] According to some embodiments, the bending unit may comprise a slit extending through the body along the extension of the channel. The slit may be adapted for inserting an LED filament into the channel.

[0021] The slit may extend along the entire channel. The slit may further function as an opening for inserting the LED filament into the channel. Such a slit may allow the LED filament to be inserted sideways into the channel. Thus, the entire LED filament does not have to be fed through the channel to the desired portion. Furthermore, the LED filament may be placed in the bending unit without being fed through the channel in large part, so that the LED filament may not be bent unnecessarily.

[0022] For example, the width of the slit may be larger than the diameter of the LED filament, but smaller than the inner diameter or width of the channel. Alternatively, the width of the slit may be slightly smaller than the diameter of the LED filament. In such an embodiment, if the LED filament has a certain flexibility (e.g., if it comprises a flexible encapsulant), the LED filament may be inserted into the channel. Thus, the LED filament may be fixed in the bending unit.

[0023] The body of the bending unit may have surfaces defining the walls of the channel, the shape of the walls may be adapted to the circumference of a certain type of LED filament, so that said type of LED filament fits into the channel.

[0024] According to some embodiments, the surfaces defining the walls of the channel may comprise at least one recess. For example, the surfaces of the walls may comprise at least two recesses. In particular, the surfaces may comprise at least three recesses. Such embodiments may provide improved thermal management. In particular, the recesses may allow air to flow within the bending unit, thereby removing heat from the LED filament.

[0025] According to some embodiments, the at least one recess may extend along an elongate portion of the channel, for example, the at least one recess may extend along the entire length of the channel, such embodiments may provide further improved temperature management.

[0026] According to some embodiments, the surfaces of the body defining the walls of the channel may have a reflectivity of at least 85%.

[0027] Specifically, the surface / wall may have a reflectance of at least 90%. More specifically, the surface / wall may have a reflectance of at least 92%.

[0028] High reflectivity can allow light to be reflected and emitted at the ends of the flex units. If light is reflected instead of absorbed by the flex units, less heat can be generated.

[0029] According to some embodiments, the surfaces defining the walls of the channels may be coated with a coating layer comprising a metal. For example, the coating layer may comprise silver or aluminum. The metal coating may improve the reflectivity of the surface. The metal coating may also improve the thermal conductivity of the surface.

[0030] For example, the metal layer may be applied using a deposition technique such as physical vapor deposition or chemical vapor deposition.

[0031] According to some embodiments, the surfaces defining the walls of the channels may be coated with a coating layer comprising a polymer and light scattering particles. For example, the polymer may be silicone. The light scattering particles may comprise, for example, barium sulfate (BaSO4), aluminum (III) oxide (Al2O3), and / or titanium dioxide (TiO2). The polymer coating with light scattering particles may improve the light distribution of the bending unit. Such a coating layer may further increase the reflectivity of the surface.

[0032] For example, the coating layer may include a matrix material, such as a polymer matrix that contains particles. Such particles may include silver-based particles, aluminum-based particles, or light scattering particles, as described above.

[0033] According to some embodiments, the portion of the LED filament disposed within the channel may comprise two or more LEDs.

[0034] For example, the portion of the LED filament disposed within the channel may include four or more LEDs. Specifically, the portion of the LED filament disposed within the channel may include six or more LEDs. More specifically, the portion of the LED filament disposed within the channel may include eight or more LEDs.

[0035] According to some embodiments, the arrangement may comprise a plurality of bending units, each of which may be adapted to induce a bend in the LED filament.

[0036] For example, the plurality of bending units may include at least three bending units. Specifically, the plurality of bending units may include at least five bending units. More specifically, the plurality of bending units may include at least seven bending units.

[0037] Specifically, each bending unit may be adapted to induce a bend in a separate portion of the LED filament. By using multiple bending units, multiple bends can be induced in a single LED filament. Furthermore, by using multiple bending units, multiple bends can be induced in a single LED filament that would not otherwise be possible (i.e., without the bending units) without reliability issues.

[0038] Using multiple bending units, the LED filament may be arranged, for example, in a crown shape, a zigzag shape, or a spiral shape, it will be appreciated that many other shapes and configurations may be possible using bending units.

[0039] According to some embodiments, at least a partial curvature of the channel may be rounded such that the channel has a U-shape.

[0040] The rounded bends of the channel may prevent sharp bends in the LED filament, which may cause distortion in some LED filaments, improving the reliability of the LED filament configuration.

[0041] Furthermore, the bending unit may form more than one bend. For example, the bending unit may have a serpentine shape. The bending unit may further have a helical shape forming one or more loops.

[0042] According to some embodiments, the bending unit may have a tubular shape, in other words, the bending unit may have a rounded hollow shape.

[0043] According to some embodiments, a lighting device may be provided. The lighting device may comprise an LED filament arrangement as described above with reference to any of the previous embodiments. The lighting device may further comprise an at least partially light-transmissive envelope that may at least partially surround the LED filament arrangement. The lighting device may further comprise a base onto which the envelope may be mounted. The base may be adapted to be connected to a luminaire socket. The lighting device may be, for example, a lamp or a light bulb.

[0044] It should be noted that other embodiments may be envisioned that use all possible combinations of the features recited in the above embodiments, and therefore the present disclosure also relates to all possible combinations of the features referred to herein. [Brief description of the drawings]

[0045] Exemplary embodiments will now be described in more detail with reference to the accompanying drawings, in which: [Figure 1] 1 is a schematic diagram of an LED filament configuration according to some embodiments. [Diagram 2] 1 is a schematic diagram of an LED filament configuration according to some embodiments. [Figure 3a]3 shows drawings of a bending unit according to some embodiments, where FIG. 3a is a perspective view of the bending unit and FIG. 3b is a cross-sectional view taken along line AA'. [Figure 3b] 3 shows drawings of a bending unit according to some embodiments, where FIG. 3a is a perspective view of the bending unit and FIG. 3b is a cross-sectional view taken along line AA'. [Figure 4a] 4A and 4B show drawings of an LED filament configuration according to some embodiments, where FIG. 4a is a perspective view of the LED filament configuration and FIG. 4b is a cross-sectional view taken along line BB'. [Figure 4b] 4A and 4B show drawings of an LED filament configuration according to some embodiments, where FIG. 4a is a perspective view of the LED filament configuration and FIG. 4b is a cross-sectional view taken along line BB'. [Diagram 5] 1 is a schematic diagram of a cross section of a flexion unit according to some embodiments. [Figure 6a] 6A and 6B show drawings of an LED filament configuration according to some embodiments, where FIG. 6a is a perspective view of the LED filament configuration and FIG. 6b is a cross-sectional view taken along line CC'. [Figure 6b] 6A and 6B show drawings of an LED filament configuration according to some embodiments, where FIG. 6a is a perspective view of the LED filament configuration and FIG. 6b is a cross-sectional view taken along line CC'. [Figure 7] 1 is a schematic diagram of an LED filament configuration according to some embodiments. [Figure 8] 1 is a drawing of a lighting device according to some embodiments.

[0046] As shown in the figures, the sizes of elements and regions may be exaggerated for illustrative purposes and are therefore presented to illustrate the general structure of the embodiments. Like reference characters refer to like elements throughout. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which presently preferred embodiments are shown. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather, these embodiments are provided for completeness and completeness and to fully convey the scope of the invention to those skilled in the art.

[0048] With reference to FIG. 1, an LED filament configuration 100 according to some embodiments is described. The LED filament configuration 100 comprises an elongated flexible LED filament 110. The LED filament configuration 100 further comprises three bending units 120. Each bending unit comprises a body in which a channel 121 is defined or formed. A portion of the LED filament 110 is disposed within the channel of each bending unit. The channel 121 of the bending unit 120 is curved to cause a bend in the LED filament 110. In the particular embodiment shown in FIG. 1, the bending units 120 are disposed such that the LED filament 110 forms a zigzag shape (i.e., alternating sharp left-right bends or up-down bends, etc.). In this embodiment, the portions of the LED filament 110 outside and between the bending units 120 are substantially straight.

[0049] Furthermore, in this embodiment, the bending unit 120 is at least partially light-transmitting. Specifically, the bending unit 120 is transparent, which means that the portion of the LED filament 110 disposed within (inside) the channel 121 of the bending unit 120 can be seen through the bending unit 120. Because the bending unit 120 is transparent, light emitted by the portion of the LED filament 110 disposed within the bending unit 120 can be emitted through the bending unit 120.

[0050] Referring to FIG. 2, an LED filament configuration 200 according to some embodiments is illustrated.

[0051] The LED filament configuration 200 shown in Fig. 2 comprises an LED filament 210, which may be equivalent to the LED filament 110 as described with reference to Fig. 1. The LED filament configuration 200 further comprises five bending units 220. As described above with reference to Fig. 1, each bending unit comprises a channel within which a portion of the LED filament 220 is disposed. However, these channels are not visible in Fig. 2, since the bending units 220 in this embodiment are light-tight. Furthermore, the curvature of the channel and the configuration of the bending units result in an S-like curvature of the LED filament 210, with the bending units 220 disposed at the outermost points of each bend of the S-bend.

[0052] A bending unit 320 according to some embodiments is described with reference to Figures 3a and 3b. Figure 3a is a perspective view of the bending unit 320. Figure 3b is a cross-sectional view of the bending unit 320 along the line A-A', which is perpendicular to the local extension of the channel.

[0053] The bending unit 320 comprises a body 322 having a channel 321 formed therein. In this embodiment, the body 322 is light transmissive. It will be appreciated that in other embodiments, the body may be at least partially light-blocking. Additionally, the bending unit 320 (specifically the body 322) is rated to have a resistance of at least 200 Wm -1 K -1 For example, the flexure unit 320 may include any highly thermally conductive material, such as aluminum, iron, steel, or copper.

[0054] The bending unit 320 has a surface 323 that defines the walls of the channel 321. The surface 323 may be highly reflective, for example having a reflectivity of at least 85%. The surface 323 may have an even higher reflectivity, for example a reflectivity of 90%, 92% or even higher.

[0055] The surface 323 may further include a coating layer. The coating layer may include a metal, such as silver or aluminum. The coating layer may also include a polymer, such as silicone, and light scattering particles, such as barium sulfate (BaSO4), aluminum(III) oxide (Al2O3), or titanium dioxide (TiO2).

[0056] The bending unit 320 in this embodiment has a bent / curved tubular shape. As can be seen in Fig. 3b, the cross section of the bending unit 320 has a substantially circular circumference. Furthermore, the surfaces 323 defining the walls of the channel are also substantially circular in cross section. It is understood that the channel and the body of the bending unit may have cross sections of different shapes in other embodiments. In particular, the channel may be shaped to accommodate the type of LED filament that is intended to be used.

[0057] 4a and 4b, an LED filament configuration 400 according to some embodiments is described. Fig. 4a is a perspective view of the LED filament configuration 400. Fig. 4b is a cross-sectional view taken along line B-B', which is perpendicular to the bending unit 420 and the local extension of the LED filament 410.

[0058] The LED filament 410 may be equivalent to any of the LED filaments described with reference to the previous figures. The bending unit 420 may be equivalent to any of the aforementioned bending units described with reference to Figures 1-3, except that it comprises a slit 424. The slit 424 provides an opening extending along the extension of the bending unit 420 between the outside of the bending unit 420 and the channel. The slit 424 is adapted to allow insertion of the LED filament 410 into the channel. Specifically, in this embodiment, the slit 424 is adapted to allow insertion of the LED filament 410 sideways into the channel. To insert the LED filament 410 sideways into the channel, the LED filament 410 may be aligned parallel to the slit 424. A (light) force may be applied to either the LED filament or the bending unit (or both) to compress them, thereby inserting the LED filament 410 into the slit 424. Therefore, the bending unit 420 may have a certain flexibility / elasticity, which may allow the bending unit 420 to deform slightly upon insertion and then return to its original shape.

[0059] In other embodiments, the LED filament may be threaded into a channel of the bending unit by inserting one end of the LED filament into one end of the channel and threading it through the channel until the portion that will cause the bend is within the channel.

[0060] With reference to Fig. 5, a bending unit 520 according to some embodiments is described. Fig. 5 is a cross-sectional view of a bending unit similar to that shown in Figs. 3b and 4b. The bending unit 520 may be equivalent to the bending unit 420 described with reference to Fig. 4, except that the surface 523 defining the wall of the channel comprises a number of recesses 525. The recesses 525 may extend along the entire length of the channel. Alternatively, the recesses 525 may extend only along some parts of the channel.

[0061] It will be appreciated that flexure units without slits, such as those shown in Figures 1, 2, 3a, and 3b, may include recesses as described herein with reference to Figure 5. Additionally, different embodiments may include fewer or more recesses along the inner surface 523 (i.e., the surface defining the walls of the channel).

[0062] An LED filament configuration 600 according to some embodiments is illustrated with reference to Figure 6. Figure 6a is a perspective view of the LED filament configuration 600. Figure 6b is a cross-sectional view taken along line CC', similar to the cross-sectional views of Figures 3b, 4b, and 5.

[0063] The LED filament configuration 600 comprises a bending unit 620, which may be equivalent to the bending units 120 or 220 described above with reference to Figures 1 and 2. The LED filament configuration 600 may further comprise an LED filament 610.

[0064] The LED filament 610 comprises a flexible carrier 611 on which a number of LEDs 612 are arranged. The LEDs 612 are arranged in a row on a first surface 613 of the carrier 611. In particular, the LEDs 612 are arranged along the elongation direction of the LED filament (i.e., along the elongation). An encapsulant 614 covers (encapsulates) the carrier 611 and the LEDs 612. In particular, both the first surface 613 and the surface opposite to the first surface of the carrier 611 are covered by the encapsulant 614, giving the LED filament 610 a round shape (i.e., a round cross-section as shown in FIG. 6b). The carrier 611 may be at least partially light-transmitting, for example translucent or transparent.

[0065] The LED 612 is configured to emit light that may be referred to as LED light. The LED 612 may be configured to emit, for example, blue light (blue LED) or ultraviolet light (UV LED). Alternatively, a red-green-blue (RGB) LED may be used that combines red, green, and blue light to emit a composite light. In particular, in embodiments using blue or UV LEDs, the encapsulant 614 may include a wavelength-converting (luminescent) material. Such a material may absorb light of wavelengths within a certain range and re-emit the light in a second, different wavelength range, which may be referred to as converted light. The process of absorbing light and re-emitting it at a different wavelength may be referred to as converting the wavelength of the light. The light emitted by the LED filament may be referred to as LED filament light. The LED filament light may include LED light and / or converted light.

[0066] A portion of the LED filament 610 is disposed within a channel of the bending unit 620. In this embodiment, the portion of the LED filament 610 that is covered by (i.e., disposed within) the bending unit 620 comprises four LEDs, however, this is only one example and the bending unit may surround more or less than four LEDs.

[0067] Although FIG. 6a shows ten LEDs 612 arranged in a row on the carrier 611, in other embodiments the LED filament may comprise fewer or more LEDs which may be arranged on one or more sides of the carrier in one or more rows or other configurations.

[0068] It will be understood that in general, an LED filament may comprise a plurality of light emitting diodes (LEDs) that provide LED filament light and are arranged in a linear array. Preferably, the LED filament has a length L and a width W, where L>5W. The LED filament may be arranged in a straight configuration or in a non-straight configuration, such as a curved configuration, a 2D / 3D swirl, or a spiral. Preferably, the LEDs are arranged on an elongated carrier, such as a substrate, which may be flexible (e.g., made of a film or foil, e.g., of a polymer or metal). The bending unit described in the present disclosure may assist in arranging the LED filament in such a configuration by inducing a bend in the LED filament.

[0069] Where the carrier comprises a first major surface and an opposite second major surface, the LED may be disposed on at least one of these surfaces. The carrier may be reflective or light transmissive, for example translucent and preferably transparent.

[0070] The LED filament may include an encapsulant at least partially covering at least a portion of the plurality of LEDs. The encapsulant may also at least partially cover at least one of the first major surface or the second major surface. The encapsulant may be a polymeric material, which may be flexible, such as, for example, silicone. Furthermore, the LEDs may be configured to emit LED light, for example, of various colors or spectrums. The encapsulant may include a luminescent material configured to at least partially convert the LED light to converted light. The luminescent material may be a phosphor, such as an inorganic phosphor and / or a quantum dot or quantum rod.

[0071] An LED filament may include multiple sub-filaments.

[0072] With reference to Figure 7, an LED filament configuration 700 according to some embodiments is described. The LED filament configuration 700 comprises an LED filament 710, which may be equivalent to the LED filament 610 described with reference to Figure 6. The LED filament configuration 700 further comprises a plurality of bending units 720. More specifically, the LED filament configuration 700 comprises seven bending units 720. The bending units 720 may be equivalent to any of the bending units described above with reference to Figures 1-6.

[0073] In this embodiment, the portion of the LED filament 710 that is not covered by the bending unit 720 (i.e., not disposed in its channel) is of similar length and has a slight curvature or is not curved (i.e., is substantially straight). Furthermore, the bending units 720 are arranged in alternating orientations such that the LED filament 710 forms a zigzag shape. Furthermore, two end points of the LED filament 710 are arranged adjacent to each other such that the zigzag shape configuration 700 forms a crown-like shape. Such configurations where the bends have the appearance of sharp corners can be built using the bending unit with improved reliability compared to similar configurations without the bending unit.

[0074] With reference to FIG. 8, a lighting device 830 according to some embodiments is illustrated.

[0075] The lighting device 830 comprises an LED filament configuration 800. In this embodiment, the LED filament configuration 800 may be equivalent to the LED filament configuration 700 described with reference to Figure 7. However, other shapes of LED filament configurations may be used as shown in other embodiments.

[0076] The lighting device 830 further comprises an at least partially light-transmitting envelope 831 that encloses the LED filament arrangement 800. In particular, the envelope 831 is transparent. The envelope 831 is mounted on a base 832. The base 832 is adapted to be connected to a luminaire socket. The illustrated embodiment is adapted to be connected to an Edison-type socket. However, other embodiments may be adapted to other types of sockets.

[0077] To place the LED filament arrangement 800 within an envelope 831 (or light bulb), the arrangement 800 is connected to a holding means 833, which is also connected to a base 832. Furthermore, electrical contacts 834 are provided for connecting end points of the LED filament 810 to the base 832, in order to supply power to the LED filament 810.

[0078] Those skilled in the art will appreciate that the present invention is in no way limited to the preferred embodiments described above, but rather many modifications and variations are possible within the scope of the appended claims.

[0079] Although the features and elements are described above in particular combinations, each feature or element can be used alone without the other features and elements, or can be used in various combinations with or without the other features and elements.

[0080] Furthermore, variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, upon study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that certain features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage.

Claims

1. an elongated flexible LED filament having a plurality of LEDs disposed along an elongate portion of the LED filament; 1. A filament configuration for a light emitting diode, or LED, comprising: a bending unit having a body, the body having a channel formed therein, the channel being at least partially curved; a portion of the LED filament is disposed within the channel of the bending unit, the bending unit being adapted to induce a bend in the LED filament and to hold the LED filament in a bent configuration; An LED filament configuration, wherein the length of the bending unit is 0.05 to 0.3 times the length of the LED filament.

2. 2. The LED filament configuration of claim 1, wherein the length of the bending unit is 0.08 to 0.25 times the length of the LED filament.

3. 3. An LED filament arrangement according to claim 1 or 2, wherein the bending unit is at least partially light-transmitting.

4. 3. An LED filament arrangement according to claim 1 or 2, wherein the bending unit is at least partially light-shielding.

5. The bending unit has a resistance of at least 200 Wm －１ K －１ 5. An LED filament arrangement according to claim 1 , comprising a material having a thermal conductivity of

6. 6. An LED filament arrangement according to claim 1, wherein the bending unit comprises a slit for inserting the LED filament into the channel, the slit extending along an elongate portion of the channel.

7. 7. An LED filament configuration according to claim 1, wherein the surface of the body defining the walls of the channel comprises at least one recess.

8. The LED filament configuration of claim 7 , wherein the recess extends along an extension of the channel.

9. 9. An LED filament configuration according to claim 1, wherein the surfaces of the body defining the walls of the channel have a reflectivity of at least 85%.

10. 10. An LED filament configuration according to claim 1, wherein the surfaces of the body defining the walls of the channel are covered with a coating layer comprising a metal or a polymer and light scattering particles.

11. 11. An LED filament arrangement according to claim 1, wherein the portion of the LED filament arranged in the channel of the bending unit comprises two or more LEDs.

12. 12. An LED filament arrangement according to any one of the preceding claims, further comprising a plurality of bending units, each bending unit adapted to induce a bend in the LED filament.

13. 13. An LED filament configuration according to any one of the preceding claims, wherein at least a partial bend in the channel is rounded such that the channel has a U-shape.

14. 14. An LED filament arrangement according to any one of the preceding claims, wherein the bending unit has a tubular shape.

15. An LED filament arrangement according to any one of claims 1 to 14; an at least partially optically transparent envelope at least partially surrounding the LED filament arrangement; a base to which the envelope is attached, the base being adapted to be connected to a luminaire socket.

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