LED filament arrangement

Abstract

A light emitting diode, LED, filament arrangement (100), comprising at least one LED filament (110) comprising an array of a plurality of light emitting diodes, LEDs. The at least one LED filament (110) is of an elongated shape, and is at least partially extending along an axis, A. The at least one LED filament comprises at least one branch (120, 121) extending from the elongated LED filament (110) and is arranged at an angle, , to the axis A.

Claims

1. A light emitting diode, LED, filament arrangement, comprising n sets of LED filaments, each filament comprising an array of a plurality of light emitting diodes, LEDs, wherein the LEDs are attached to a single carrier, wherein the at least one LED filament is of an elongated shape, and at least partially extends along an axis, A, and wherein each LED filament comprises a bifurcation from which the LED filament forks into at least two branches of which at least one of the branches is arranged at an angle with respect to the axis A, the angle represented by the symbol a, wherein each LED filament comprises an encapsulant integrally enclosing the LED filament including the at least two branches and the bifurcation, and wherein at least one LED filament of a (k+1).sup.th set of LED filaments constitutes at least one branch of the at least one LED filament of a k.sup.th set of LED filaments, in an iterative manner from k=1, 2, . . . , n1, such that the n sets of LED filaments constitute a tree structure of LED filaments with at least one bottom end LED filament branch and two or more opposite top end LED filament branches of the tree structure.

2. The LED filament arrangement according to claim 1, wherein the LEDs in the array are arranged to provide a continuous light distribution over an entirety of each LED filament including the at least two branches.

3. The LED filament arrangement according to claim 1, wherein a line of emission of the array of a plurality of LEDs continues through the branches.

4. The LED filament arrangement according to claim 1, wherein at least a first branch of the plurality of branches has a different length than a second branch of the plurality of branches.

5. The LED filament arrangement according to claim 1, wherein the at least one LED filament is Y-shaped.

6. The LED filament arrangement according to claim 1, wherein the at least one LED filament is X-shaped.

7. The LED filament arrangement according to claim 1, wherein the LEDs in the at least two branches of the plurality of LEDs in the at least one LED filament are connected in series.

8. The LED filament arrangement according to claim 1, wherein the LEDs of at least a first set of LEDs of the plurality of LEDs and the LEDs of at least a second set of LEDs of the plurality of LEDs in the at least one LED filament are connected in parallel.

9. The LED filament arrangement according to claim 1, wherein the LEDs of at least a first set of LEDs of the plurality of LEDs and the LEDs of at least a second set of LEDs of the plurality of LEDs are configured to emit light with at least one of the same color temperature and the same luminous intensity.

10. The LED filament arrangement according to claim 1, wherein the LEDs of at least a first set of LEDs of the plurality of LEDs and the LEDs of at least a second set of LEDs of the plurality of LEDs are configured to emit light with at least one of different color temperature and different luminous intensity.

11. The LED filament arrangement according to claim 10, wherein the encapsulant comprises a luminescent material and is configured to at least partly convert the light emitted by the plurality of LEDs, or the encapsulant comprises a scattering material for scattering the light emitted by the plurality of LEDs.

12. The LED filament arrangement according to claim 1, wherein the angle, , between the at least one branch and the axis A is within a range of 10-80 degrees.

13. A light emitting diode, LED, filament unit, comprising a plurality of LED filament arrangements according to claim 1, wherein the plurality of LED filament arrangements is coupled such that at least a first LED filament of the plurality of LED filament arrangements is in physical contact with at least a second LED filament of the plurality of LED filament arrangements.

14. The LED filament arrangement according to claim 1, wherein the angle, , between the at least one branch and the axis A is within a range of 20-60 degrees.

15. The LED filament arrangement according to claim 1, wherein the angle, , between the at least one branch and the axis A is within a range of 30-50 degrees.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative and non-limiting detailed description of embodiments of the present invention. Reference will be made to the appended drawings, on which:

(2) FIG. 1 schematically shows a LED filament arrangement according to an exemplifying embodiment of the present invention,

(3) FIGS. 2a-b schematically show a LED filament arrangement according to an exemplifying embodiment of the present invention,

(4) FIGS. 3a-b schematically show a cross-sectional view of a LED filament arrangement according to an exemplifying embodiment of the present invention,

(5) FIG. 4 schematically shows a LED filament arrangement according to exemplifying embodiments of the present invention,

(6) FIG. 5 schematically shows a LED filament unit according to exemplifying embodiments of the present invention,

(7) FIGS. 6a-c schematically shows a LED filament device according to an exemplifying embodiment of the present invention.

(8) All the figures are schematic, generally not to scale, and generally only show parts which are necessary in order to elucidate the invention, whereas other parts may be omitted or merely suggested.

DETAILED DESCRIPTION

(9) FIG. 1 shows a schematic view of a LED filament arrangement 100 according to an exemplifying embodiment of the present invention. The LED filament arrangement 100 comprises a LED filament 110 elongated along an axis A. Further, the LED filament 110 also comprises branches two 120, 121 extending at the bifurcation from the elongated LED filament 110. It should be noted that the number of branches of the LED filament 110 is arbitrary, and that the two branches 120, 121 are shown as an example.

(10) The branch 120 of the LED filament 110 is extending from the axis A at an angle . The angle may preferably be within the range of 10-80 degrees, preferably 20-60 degrees, and most preferably 30-50 degrees. The LED filament 110 in the present embodiment comprises two branches 120, 121, extending in similar angles from the axis a. However, branches 120, 121 of the LED filament 110 may comprise different angles and an asymmetrical shape may thus be achieved.

(11) The LED filament arrangement 100 comprises a plurality of LEDs (not shown), which may be attached to a carrier. The carrier may be a substrate which may be flexible or rigid.

(12) The LED filament 110 further comprises an encapsulant comprising a translucent material, wherein the encapsulant at least partially encloses the plurality of LEDs. For example, the encapsulant may fully enclose the plurality of LEDs, that is including the part of the bifurcation. The encapsulant is preferably a polymer material, for example made of silicon.

(13) The LEDs may be direct emitting LEDs which provide a color. The LEDs may be RGB, UV or blue LEDs. Further combinations of LEDs, e.g. UV LEDs and blue light LEDs, may be used. The LEDs may also comprise laser diodes.

(14) The color temperature of the white light is preferably in the range of 1800 to 6000 K, more preferably in the range from 2000 to 5000 K, most preferably in the range from 2200 to 4000 K such as for example 2300 K or 2700 K. The white light has preferably a CRI of at least 75, more preferably at least 80, most preferably at least 85 such as for example 90 or 92.

(15) The encapsulant of the LED filament 110 may comprise a luminescent material, which is configured to emit light under external energy excitation. The UV/blue LED light may be partially or fully absorbed by the luminescent material and converted to light of another color e.g. green, yellow, orange and/or red. The luminescent material may for example comprise; inorganic phosphor, organic phosphor and/or quantum dots/rods.

(16) FIGS. 2a and 2b shows further embodiments of LED filament arrangements 100. It should be noted that the LED filament arrangement 100 of FIGS. 2a and 2b may be similarly configured as the LED filament arrangement 100 described in connection with FIG. 1, and it is referred to FIG. 1 for an increased understanding. FIG. 2a displays a Y-shaped LED filament arrangement 100 and FIG. 2b displays an X-shaped LED filament arrangement 100 (although not shown, the LED filament arrangement 100 may alternatively have a K-shape). The LED filaments 110 illustrated in FIGS. 2a and 2b represents embodiments in which a plurality of branches are provided. As seen, the LED filaments 110 may comprise a different number of branches 120, 121. The branches 120, 121 of a LED filament 110 may, for example, be directed in different angles and directions, and may be of different lengths.

(17) As exemplified in FIG. 2a, the Y-shaped LED filament 110 may comprise branches 120, 121 of equal or unequal length, while still maintaining a Y-shape.

(18) As illustrated in FIG. 2b, a symmetrical LED filament 110 of an X-shape is provided such that a plurality of end portions in both the top and bottom of the LED filament 110 is achieved. The X-shaped LED filament 110 comprises four branches 120, 121, 122, 123, having the bifurcation in the center of the X-shaped LED filament. The X-shaped LED filament 110 could also be asymmetric in the same manner as the Y-shaped LED filament 110 discussed in regard to FIG. 2a.

(19) FIGS. 3a and 3b schematically show cross sections of a LED filament 110 of the LED filament arrangement 100, comprising an array or chain of LEDs 130. The LEDs are arranged in the LED filament arrangement 100 such that the line of emission of the array of a plurality of LEDs continues through the branches.

(20) The array of LEDs 130 may comprise a plurality of adjacently arranged LEDs 130 wherein a respective wiring is provided between each pair of LEDs 130.

(21) FIG. 3a displays an embodiment in which all LEDs 130 are connected in series.

(22) FIG. 3b displays an embodiment of a LED filament arrangement 100 comprising two branches 120, 121. A plurality of the LEDs, among the array of LEDs 130, may be further defined as a set of LEDs 131, 132, 133. Here, the LED filament 110 comprises individual sets of LEDs 131, 132, where the sets of LEDs 131, 132 are connected in parallel. The set of LEDs 133 of the unbranched portion of the LED filament 110 is connected in series with the sets of LEDs 131, 132 of the branches.

(23) Other embodiments may see further combinations of sets or individual LEDs connected in parallel, series or any combination thereof. The structure of the LED filament may for example cause different sections of the LED filament arrangement 100 to be of different luminous intensity.

(24) FIG. 4 shows an embodiment of a LED filament arrangement 100 in which one portion 105 of the LED filament 110 is of a different color temperature, or a different luminous intensity, than the branches 120, 121 of the LED filament 110. It is understood that other sections or combinations of sections of the LED filament 110 may be arranged for having different color temperature, or luminous intensity. For example, different colors (temperatures) may be obtained by using LEDs emitting different colors and/or using different luminescent materials (e.g. phosphors such as a red phosphor or the combination of a yellow and red phosphor) in different parts of the LED filament arrangement 100, e.g. in an encapsulant of the LED filament 110.

(25) FIG. 5 displays a schematic representation of an embodiment of a LED filament unit 140. As illustrated, the LED filament unit 140 may comprise two LED filament arrangements 100, 101, which are in physical, and electrical, connection. In this exemplified illustration, two end portions of the LED filaments 100, 101 are in contact, but other configurations are also possible. Further, the LED filament unit 140 may comprise any plurality of LED filament arrangements 100, 101. Further, the LED filaments 100, 101 may be arranged in any desirable manner in which at least one LED filament arrangement 100 is in physical contact with at least one other LED filament arrangement 101.

(26) FIGS. 6a, 6b and 6c schematically show a LED filament device 150 which comprises n sets of LED filaments 160. As illustrated, each set of LED filaments 160 comprises at least one branched LED filament 110. The branched LED filament 110 of the (k+1).sup.th set of LED filaments 160 constitutes a branch of the branched LED filament 110 of the k.sup.th set of LED filaments 160, wherein k represents a set of LED filaments and where k=1, 2, . . . , n1. Consequently, the set of LED filaments 160 can be understood to represent a layer in a tree like structure. As depicted in FIGS. 6a, 6b and 6c, this iterative structure forms a tree-like shape where each branch of a branched LED filament 110 is further branched into new LED filaments 110, and so on. As illustrated, the length L of the LED filament 110, which extends along an axis A may be of varying length. In the embodiment displayed in FIG. 6a, the length L is decreased for each set of LED filaments 160 in the tree-like shape of the LED filament device 150. The length L is preferably in the range from 2 cm to 10 cm.

(27) FIG. 6b schematically shows a similar LED filament device wherein the length L is the same for each set of LED filaments 160 of the tree-like structure.

(28) FIG. 6c schematically shows a similar LED filament device wherein the length L is increasing for each set of LED filaments 160 of the tree-like structure.

(29) The length L may thus be utilized to create numerous shapes and structures, exemplified in FIGS. 6a, 6b and 6c.