Abstract
The present invention relates to an LED filament (100) comprising a carrier (110) comprising a plurality of LEDs (140) arranged in at least two columns of LEDs (150, 160). The plurality of LEDs (140) are grouped into at least two different subsets of LEDs (120, 130), wherein a first subset of the LEDs (120) is configured to emit light of a first color temperature, CT1, and a second subset of the LEDs (130) is configured to emit light of a second color temperature, CT2, CT2 being different from CT1. The LEDs (140) of the at least two different subsets of LEDs (120, 130) are arranged in an alternating intersecting configuration in the at least two columns of LEDs (150, 160) such that each column (150) comprises alternating segments (132, 124) configured to emit light of the first and the second color temperatures, respectively.
Claims
1. An LED filament comprising: a carrier comprising a plurality of LEDs arranged in at least two columns of LEDs; wherein the plurality of LED are grouped into at least two different subsets of LEDs, wherein a first subset of the LEDs is configured to emit light of a first color temperature, CT1, and a second subset of the LEDs is configured to emit light of a second color temperature, CT2, CT2 being different from CT1; and wherein the LEDs of the at least two different subsets of LEDs are arranged in an alternating intersecting configuration in the at least two columns of LEDs such that each column comprises alternating segments configured to emit light of the first and the second color temperatures, respectively.
2. The LED filament according to claim 1, wherein each subset of LEDs comprises a plurality of LEDs, wherein the plurality of LED in a subset of LEDs is electrically connected such that each subset of LEDs is independently controllable.
3. The LED filament according to claim 1, wherein a distance between the two columns of LEDs is in a range of 0.05 to 3 mm.
4. The LED filament according to claim 1, wherein a number of LEDs per segment is at least 3, preferably at least 5, more preferably at least 7.
5. The LED filament according to claim 1, wherein a length of each segment is in a range of 5 to 30 mm.
6. The LED filament according to claim 1, wherein a length of the LED filament is in a range of 3 to 100 cm.
7. The LED filament according to claim 1, wherein the first subset of LEDs is encapsulated by a first encapsulant comprising a first luminescent material, wherein the second subset of LEDs is encapsulated by a second encapsulant comprising a second luminescent material, and wherein the first and second encapsulants are different.
8. The LED filament according to claim 1, wherein the carrier is flexible.
9. The LED filament according to claim 1, wherein the carrier is light transmissive.
10. The LED filament according to claim 1, wherein the carrier is reflective and having two opposing surfaces, wherein the at least two columns of LEDs are arranged on a first surface of the two opposing surfaces and wherein a second surface of the two opposing surfaces comprises at least two columns of LEDs arranged as the at least two columns of LEDs on the first surface.
11. The LED filament according to claim 1, wherein CT1>2500 K and CT2<2500 K, and wherein CT1-CT2>500 K.
12. A lamp comprising an LED filament according to claim 1.
13. The lamp according to claim 12, wherein the LED filament is arranged as a helix.
14. The lamp according to claim 13, wherein the two columns of LEDs are arranged at a distanced from each other and wherein the helix has a pitch, wherein D<0.3 P, preferably D<0.2 P, more preferably D<0.1 P.
15. The lamp according to claim 12, further comprising a controller configured to independently control the first subset of LEDs and the second subset of LEDs.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The above and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiments of the invention. The figures should not be considered limiting the invention to the specific embodiment;
[0025] instead they are used for explaining and understanding the invention.
[0026] FIG. 1 schematically illustrates an LED filament comprising a plurality of LEDs arranged in two columns.
[0027] FIG. 2 schematically illustrates an LED filament comprising two columns, each column comprising two segments.
[0028] FIG. 3 schematically illustrates an LED filament comprising two columns, each column comprising three segments.
[0029] FIG. 4 schematically illustrates an LED filament comprising a plurality of LEDs and colored LEDs arranged in two columns.
[0030] FIG. 5a schematically illustrates an LED filament comprising a plurality of LEDs arranged on two opposing surfaces of a carrier.
[0031] FIG. 5b schematically illustrates the LED filament of FIG. 5a wrapped around a roll.
[0032] FIG. 6 schematically illustrates a lamp comprising the LED filament shown in FIG. 2.
[0033] FIG. 7a schematically illustrates a lamp comprising an LED filament arranged in a helix.
[0034] FIG. 7b schematically illustrates a magnified view of the LED filament of the lamp shown in FIG. 7a.
[0035] As illustrated in the figures, the sizes of layers and regions are exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of embodiments of the present invention. Like reference numerals refer to like elements throughout.
DETAILED DESCRIPTION
[0036] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, 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 fully convey the scope of the invention to the skilled person.
[0037] In connection with FIG. 1, an LED filament is illustrated. In FIG. 1, directions Y and X respectively indicates a longitudinal and a horizontal direction of the LED filament 100. In FIG. 1, direction Z indicates a direction perpendicular to the X and Y directions. The LED filament 100 shown in FIG. 1 comprises a carrier 110. The carrier 110 may have a one-dimensional shape having two opposing surfaces. The carrier 110 may have any other shape. FIG. 1 shows a front surface of the carrier 110. The carrier 110 may be a substrate. The carrier 110 may be flexible such as a flexible substrate. The carrier 110 may be light transmissive. The carrier 110 may be formed of a polymer and/or polyimide.
[0038] FIG. 1 shows that the carrier 110 comprises a plurality of LEDs 140. The plurality of LEDs 140 may be arranged on a surface of the carrier 110. The plurality of LEDs 140 may be arranged on the surface of the carrier 110 in a manner which per se is known in the art. For instance, the plurality of LEDs 140 may be attached via a glue or a solder to the carrier 110. In the case that the carrier 110 has two-opposing surfaces, each of the two opposing surfaces of the carrier 110 may comprise a plurality of LEDs 140. The plurality of LEDs 140 is arranged in at least two columns of LEDs 150 and 160. FIG. 1 shows that the plurality of LEDs 140 is arranged in two columns of LEDs 150 and 160. The two columns of LEDs 150 and 160, shown in FIG. 1, extend along the Y direction. The plurality of LEDs 140 may be arranged in more than two columns of LEDs 150 and 160 such as three or four columns. A distance (D) between the two columns of LEDs 150, 160 may be in a range of 0.05 to 3 mm. A length (LF) of the LED filament 100 may be in a range of 3 to 100 cm.
[0039] FIG. 1 further shows that the plurality of LEDs 140 is grouped into two different subsets of LEDs 120, 130. Each subset of LEDs 120, 130 may comprise a plurality of LEDs 140. The plurality of LEDs in subset of LEDs 120, 130 may be electrically connected such that subset of LEDs 120, 130 may independently be controllable. FIG. 1 shows individual LEDs such as LEDs 142, 144, and 146 which are electrically connected to each other. The plurality of LEDs 140 may be connected to each other in a manner which per se is known in the art. For instance, the plurality of LEDs 140 may be connected via wirebonds and/or an electrical circuit on the carrier 110. A number of LEDs per segment may preferably be at least 3. The number of LEDs per segment may more preferably be at least 5. The number of LEDs per segment may most preferably be at least 7. The plurality of LEDs 140 may be grouped into more than two different subsets of LEDs 120, 130 such as three subsets or four subsets. A first subset of the LEDs 120, shown in FIG. 1, is configured to emit light of a first color temperature (CT1). A second subset of the LEDs 130, shown in FIG. 1, is configured to emit light of a second color temperature (CT2). The second color temperature (CT2) is different from the first color temperature (CT1). The first color temperature (CT1) may be larger than 2500 K (CT1>2500 K). The second color temperature (CT2) may be smaller than 2500 K (CT2<2500 K). A difference between the first and the second color temperature may be larger than 500 K (CT1-CT1>500 K). The first subset 120 of LEDs may be encapsulated by a first encapsulant comprising a first luminescent material. The second subset 130 of LEDs may be encapsulated by a second encapsulant comprising a second luminescent material. The first and the second encapsulants may be different. The encapsulant of the first subset 120 of LEDs and the encapsulant of the second subset 130 of LEDs may be different. The encapsulant of the first 120 and the second subset 130 of LEDs may have different thicknesses. Alternatively, or in combination, the concentration of the luminescent material of the encapsulant of the first 120 and the second subset 130 of LEDs may be different. Alternatively, or in combination, the type of the luminescent material of the encapsulant of the first 120 and the second subset 130 of LEDs may be different. For instance, different color temperature emitting phosphors may be deposited on different subsets of LEDs. The plurality of LEDs may further comprise colored LEDs e.g. RGB LEDs. For instance, the plurality of LEDs 140 may be grouped into three different subsets of LEDs. A first subset of LEDs may be configured to emit light of a high color temperature. A second subset of LEDs may be configured to emit light of a low color temperature. A third subset of LEDs may comprise colored LEDs e.g. RGB LEDs.
[0040] FIG. 1 further shows that the LEDs 140 of the at least two different subsets of LEDs 120, 130 are arranged in an alternating intersecting configuration in the at least two columns of LEDs 150, 160. As shown in FIG. 1, the column 150 comprises alternating segments 132 and 124 configured to emit light of the first and the second color temperatures, respectively. Accordingly, the column 160 comprises alternating segments 134 and 122 configured to emit light of the first and the second color temperatures, respectively. FIG. 1 shows that each column comprises two segments. A length (LS) of each segment may be in a range of 5 to 30 mm.
[0041] In connection with FIG. 2, another LED filament 100 is shown. The LED filament shown in FIG. 2 comprises a plurality of LEDs, arranged in two columns of LEDs 150 and 160. FIG. 2 further shows that the plurality of LEDs is grouped into two different subsets of LEDs 120, 130. FIG. 2 shows that the first column 150 comprises alternating segments 132 and 124 configured to emit light of the first and the second color temperatures, respectively. FIG. 2 further shows that the second column 160 comprises alternating segments 134 and 122 configured to emit light of the first and the second color temperatures, respectively. FIG. 2 shows that the segments 132 and 124 have the same length and the segments 122 and 134 have the same length. However, the 132 and 124 may have different lengths and the segments 122 and 134 may have different lengths.
[0042] In connection with FIG. 3, yet another LED filament 100 is shown. The LED filament shown in FIG. 3 comprises a plurality of LEDs, arranged in two columns of LEDs 150 and 160. FIG. 3 further shows that the plurality of LEDs is grouped into two different subsets of LEDs 120, 130. FIG. 3 shows that the first column 150 comprises alternating segments 132, 124 and 136. The segments 132 and 136 are configured to emit light of the first color temperature. The segment 124 is configured to emit light of the second color temperature. FIG. 3 further shows that the second column 160 comprises alternating segments 122, 134, and 126. The segment 134 is configured to emit light of the first color temperature. The segments 122 and 126 are configured to emit light of the second color temperatures. FIG. 3 shows that the segments 132, 124 and 136 have different lengths and the segments 122, 134 and 126 have different lengths.
[0043] In connection with FIG. 4, yet another LED filament 100 is shown. The LED filament 100 shown in FIG. 4 is similar to the LED filament 100 shown in FIG. 2 except that one of the two subsets of LEDs comprises colored LEDs e.g. RGB LEDs and the other subset of LEDs is configured to emit light of a color temperatures such high or low color temperature. FIG. 4 shows that the first column 150 comprises alternating segments 132 and 174 configured to respectively emit light of a color temperature and a colored light. FIG. 2 further shows that the second column 160 comprises alternating segments 134 and 172 configured to respectively emit light of the color temperature and a colored light.
[0044] In connection with FIG. 5a, an LED filament 100 comprising a carrier 110 is shown. The carrier 110 shown in FIG. 5a is reflective. The carrier 110 shown in FIG. 5a is flexible. The carrier 110 shown in FIG. 5a has two opposing surfaces 112, 114. FIG. 5a shows that the at least two columns of LEDs 150, 160 are arranged on a first surface 112 of the two opposing surfaces 112, 114. FIG. 5a further shows that a second surface 114 of the two opposing surfaces 112, 114 also comprises at least two columns of LEDs 150′, 160′. The two column of LEDs 150′, 160′arranged on the second surface 114 of the two opposing surfaces 112, 114 are arranged as the at least two columns of LEDs 150, 160 on the first surface 112. In other words, two column of LEDs 150′, 160′arranged on the second surface 114 of the two opposing surfaces 112, 114 are arranged in a similar way as the column of LEDs 150, 160 arranged on the first surface 112 of the two opposing surfaces 112, 114. FIG. 5b schematically illustrates the LED filament of FIG. 5a wrapped around a roll. The LED filament 100 shown in FIG. 5a and b may be used for decorative purposes.
[0045] In connection with FIG. 6, a lamp 200 is shown. The lamp shown in FIG. 6 comprises an LED filament 100. The LED filament 100 shown in FIG. 6 is similar to the LED filament of FIG. 2, described above. The lamp 200 further comprises an envelope 210. The envelope 210 may be a conventional envelope. The envelope 210 may be any commercially available envelope. FIG. 6 further shows that the lamp 200 comprises a cap 220. The cap 220 may allow the lamp 200 to be safely and conveniently connected to a lamp holder. The cap 210 may comprise electronic components for providing electricity to LEDs and the LED filament 100. The lamp 200 may further comprise a controller configured to independently control different subsets of LEDs such as the first subset of LEDs 120 and the second subset of LEDs 130. The controller may also be used for a lighting device or a luminaire comprising an LED filament 100 i.e. not only for the lamp 200.
[0046] In connection with FIG. 7a, another lamp 200 is shown. The lamp 200 shown in FIG. 7a comprises an LED filament 100. A magnified view of the LED filament 100 shown in FIG. 7a is shown in FIG. 7b. The LED filament 100, shown in FIGS. 7a and 7b, comprises a reflective flexible carrier 110. The LED filament 100, shown in FIGS. 7a and 7b, is arranged as a helix. The LED filament 100, shown in FIGS. 7a and 7b, comprises a plurality of LEDs arranged in two columns of LEDs 150, 160. The two columns of LEDs 150, 160 may be arranged at a distance (D) from each other. The helix may have a pitch (P). The distance D between the two columns of LEDs 150, 160 may preferably be smaller than 30% percent of the pitch (D<0.3 P). The distance D between the two columns of LEDs 150, 160 may more preferably be smaller than 20% percent of the pitch (D<0.2 P). The distance D between the two columns of LEDs 150, 160 may most preferably be smaller than 10% percent of the pitch (D<0.1 P).
[0047] Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.
