Lighting arrangement
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- SIGNIFY HOLDING BV
- Filing Date
- 2024-06-24
- Publication Date
- 2026-05-06
AI Technical Summary
Existing LED lighting arrangements face challenges in maximizing the lifetime of LEDs, particularly when providing white light with desired color temperature, as red LEDs are less stable at high temperatures, leading to performance and reliability issues.
A lighting arrangement comprising MicroLEDs with a surface area of 100 micrometers or less and standard LEDs with a surface area of 300 micrometers or more, configured to emit red and shorter wavelength lights, respectively, with a surface area ratio of 10 or higher, to improve thermal management and optical performance, while maintaining a correlated color temperature between 2000K and 6500K and a color rendering index of at least 80.
This configuration enhances the optical performance, reliability, and lifetime of the lighting arrangement by improving cooling and color stability during dimming, while allowing for a combination of cost-effective MicroLEDs and standard LEDs to achieve high-quality white light.
Smart Images
Figure EP2024067641_02012025_PF_FP_ABST
Abstract
Description
[0001] Lighting arrangement
[0002] FIELD OF THE INVENTION
[0003] The present invention generally relates to lighting arrangements configured to provide white light. More specifically, the present invention is related to a lighting arrangement comprising a plurality of light emitting diodes (LEDs).
[0004] BACKGROUND OF THE INVENTION
[0005] A trend in the development of LED lighting is the development of lighting arrangements capable of providing white light having any desired color temperature. For this purpose, the lighting arrangements are configured with a combination of a plurality of red (R), green (G) and blue (B) LED’s. While it is possible to configure a lighting arrangement with an appropriate combination of R, G and B LEDs in order to obtain such white light, a remaining issue is to maximize the lifetime of the LEDs in the lighting arrangement
[0006] SUMMARY OF THE INVENTION
[0007] It is of interest to provide a lighting arrangement that overcomes drawbacks of the prior art as discussed above.
[0008] This and other objects are achieved in a first aspect by providing a lighting arrangement having the features of the appended independent claim. Preferred embodiments are defined in the appended dependent claims.
[0009] Hence, according to the present invention, there is provided a lighting arrangement configured to provide arrangement light. The lighting arrangement comprises a carrier. A plurality of first light emitting diodes (M-LEDs) are arranged on said carrier. Each of the M-LEDs comprises a die having a first surface area (SAI), the first surface area having a largest spatial extent (SEI) that is less than or equal to 100 micrometers. The lighting arrangement further comprises a plurality of second light emitting diodes (N-LEDs) arranged on said carrier. Each of the N-LEDs comprises a die having a second surface area (SA2), the second surface area having a largest spatial extent (SE2) that is greater than or equal to 300 micrometers. Note that where reference is made to surface area, this relates to the epitaxial or epitaxy (in short ‘epi’) surface area of the die which may only be on the top surface of the die.
[0010] The M-LEDs are configured to emit first light (LG1) having a first emission peak wavelength (XI) in a wavelength range of red (R) light. The N-LEDs are configured to emit second light (LG2) having a second emission peak wavelength (X2) in a wavelength range that is shorter than the wavelength range of the first light emitted by the M-LEDs. A ratio (Rl) defined by SA2 / SA1 is equal to or larger than 10. The arrangement light is white light having a correlated color temperature (CCT) in a range from 2000K to 6500K and a color rendering index (CRI) of at least 80 or preferably at least 85.
[0011] Red light is in the wavelength range 600nm to 780nm. Near red light is in the wavelength range 600nm to 680nm.
[0012] Such a lighting arrangement provides an improved performance, especially in terms of optical performance (e.g. color point stability during dimming up)and improved lifetime / reliability. The reason is that, compared to ‘shorter wavelength’ LEDs e.g. blue and green LEDs, red LEDs are less stable when operated at high temperatures e.g. arising when dimming up LEDs. By using very small M-LEDs, i.e. MicroLEDs, the cooling (thermal management) is improved, improving in turn the performance such as the optical performance and / or the lifetime / reliability. The improved cooling is due to the fact that the small size of the M-LEDs results in a smaller output of heat when compared to larger sized LEDs. Because MicroLEDs are relatively more expensive than ‘normal’ sized LEDs e.g. in terms of assembly costs, a combination of red MicroLEDs and ‘normal’ sized ‘shorter wavelength’ LEDs, e.g. ‘normal’ sized green and blue LEDs, may be used.
[0013] By configuring embodiments of the lighting arrangement such that SEI is less than or equal to 80 micrometers, SE2 is greater than or equal to 500 micrometers and Rl is greater than or equal to 20, it is possible to obtain an even higher improvement in optical performance, reliability and lifetime for the lighting arrangement.
[0014] In embodiments, SEI may be less than or equal to 80 micrometers, preferably <70 micrometers, more preferably <60 micrometers, most preferably <50 micrometers such as for example 40 micrometers.
[0015] In embodiments, SE2 may be greater than or equal to 400 micrometers, preferably >500 micrometers, more preferably >600 micrometers, most preferably >700 micrometers such as for example 800 micrometers. In embodiments, R1 may be greater than or equal to 20, preferably >25, more preferably >30, most preferably >35 such as for example 40.
[0016] The number of M-LEDs of the plurality of M-LEDs may be X, the number of N-LEDs of the plurality of N-LEDs may be Y and wherein X is greater than or equal to 5 times Y. That is, due to the fact that the size of the M-LEDs are smaller than the size of the N-LEDs, the number of M-LEDs is much greater than the number of N-LEDs in order to enable the lighting arrangement to provide sufficient light in the ‘shorter wavelength’ region, i.e. G / B / V / UV wavelength range.
[0017] The plurality of M-LEDs may be homogeneously distributed with a first pitch (Pl) within a first region on the carrier and the plurality of N-LEDs may be homogeneously distributed with a second pitch (P2) within a second region on the carrier. The second region at least partly overlaps the first region and P2 is greater than or equal to 2 times PL In other words, by configuring the lighting arrangement with homogeneous distributions having different pitch of the M-LEDS and the N-LEDs, the performance of the lighting arrangement may be even further improved. By homogenously distributing the red M-LEDs the cooling of the red M-LEDs is further improved e.g. due to much more heatsinking space around the individual red M-LEDs.
[0018] In embodiments, the plurality of M-LEDs may be distributed / arranged within a first region on the carrier and the plurality of N-LEDs may be distributed / arranged within a second region on the carrier, wherein the second region may at least partly overlap the first region.
[0019] Each of the M-LEDs may have a first length (LI), a first width (Wl) and a first aspect ratio (ARI) defined by Ll / W 1. Each of the N-LEDs may have a second length (L2), a second width (W2) and a second aspect ratio (AR2) defined by L2 / W2, where AR2 is greater than ARI . Due to the size of the M-LEDs and N-LEDs, for the M-LEDs a high aspect ratio is not possible, while this is possible for the N-LEDs. Such a configuration is advantageous in that it may simplify electrical connections in terms of a larger distances between anode and cathode pads in the N-LEDs. By using a smaller aspect ratio for the red M-LEDs the cooling of the red M-LEDs is further improved. The reason is that the (longest) distance between the center of the die and is periphery is reduced.
[0020] The dies of the M-LEDs may be free from any luminescent material and (at least some of) the dies of the N-LEDs may be covered by a wavelength converter comprising a luminescent material. Such a luminescent material is configured to at least partly convert second LED light emitted by said plurality of N-LEDs into converted light. Because light conversion results in heat generation (due to s Stokes loss), the red M-LEDs are not impacted by this.
[0021] The M-LEDs may comprise R LEDs and the N-LEDs may comprise one or more blue (B) LEDs and one or more green (G) LEDs. That is, such a configuration of the lighting arrangement is an RGB architecture that is capable of, e.g., creating white light.
[0022] The N-LEDs may further comprise one or more phosphor converted white LEDs. Such a configuration can improve the light quality.
[0023] The number of R M-LEDs may be greater than or equal to 2 or 3 times the number of B N-LEDs and the number of R M-LEDs may be greater than or equal to 2 or 3 times the number of G N-LEDs. Such a configuration is desired in order to enable the lighting arrangement to provide sufficient light in the ‘shorter wavelength’ region i.e. G / B / V / UV wavelength range
[0024] Each N-LED may neighbored by at least 2 R M-LEDs, preferably at least 3 R M-LEDs. Such a configuration. Such configuration allows improved color homogeneity / mixed light of different colors e.g. to provide high quality white light.
[0025] Each N-LED may comprise 4 sides, wherein each side is neighbored by at least 1 R M-LED. That is, such a configuration of the lighting arrangement provides an optimal color mixing, e.g. for creating high quality white light. Such configuration allows improved color homogeneity / mixed light of different colors e.g. to provide high quality white light.
[0026] The plurality of M-LEDs may be connected with a respective anode having an anode surface area (ASA1) and a respective cathode having a cathode surface area, CSA1. The plurality of N-LEDs may be connected with a respective anode having an anode surface area (ASA2) and a respective cathode having a cathode surface area (CSA2). ASA2 may be greater than or equal to 4 times ASA1 and / or CSA2 may be greater than or equal to 4 times CSA1. In other words, the el ectrode s / electri cal tracks are scaled to a suitable configuration.
[0027] The plurality of M-LEDs may be connected via a first circuitry and the plurality of N-LEDs may be connected via a second circuitry. The lighting arrangement may comprise a controller configured to individually control the emission of the first light emitted by said plurality of M-LEDs via the first circuitry and the emission of the second light emitted by said plurality of N-LEDs via the second circuitry. In this way, the color point of the arrangement light e.g. the correlated color temperature can be adjusted. For example, the first circuitry may comprise a first number of parallel arrangements (PAI) and the second circuitry may comprise a second number of parallel arrangements (PA2) wherein PAI is greater than PA2.
[0028] In embodiments, the carrier may have a size (e.g. largest spatial extent) smaller than 10 cm, preferably smaller than 5cm.
[0029] In embodiments, a LED package may comprise the lighting arrangement.
[0030] In a second aspect there is provided a lamp or a luminaire comprising the lighting arrangement as summarized above. Such a lamp or luminaire provides corresponding effects and advantages as described above. The lamp may comprise a connector such as a cap to electrically and / or mechanically connect the lamp to a socket of a luminaire. The lamp may also have an antenna which is functionally connected to the controller allowing remote control of the lamp e.g. adjusting the intensity and / or color point / correlated color temperature e.g. using a remote control e.g. a mobile phone. The lamp may also have an envelope enveloping the lighting arrangement. The luminaire may have a mounting means to mount the luminaire to a wall or ceiling. The luminaire may comprise a light exit window such as a translucent plate to exit the arrangement light.
[0031] BRIEF DESCRIPTION OF THE DRAWINGS
[0032] This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiment(s) of the invention.
[0033] Fig. la schematically illustrates a top view of a lighting arrangement, Fig. lb schematically illustrates a cross-sectional view of the lighting arrangement illustrated in figure la,
[0034] Fig. 1c schematically illustrates a top view of an N-LED and four M-LEDs, Fig. Id schematically illustrates anodes and cathodes in an N-LED and in four M-LEDs,
[0035] Fig. le schematically illustrates a lighting arrangement connected to a controller via circuitry,
[0036] Fig. If schematically illustrates two parallel arrangements of LEDs, and Fig. 2 schematically illustrates a lamp or a luminaire.
[0037] DETAILED DESCRIPTION
[0038] As illustrated in figure la and figure lb, a lighting arrangement 100 configured to provide arrangement light comprises a carrier 151. A plurality of first light emitting diodes, M-LEDs, 101 are arranged on the carrier 151, each of the M-LEDs 101 comprising a die 111 having a first surface area, SAI, wherein the SAI has a largest spatial extent, SEI, that is less than or equal to 100 micrometers. A plurality of second light emitting diodes, N-LEDs 102 are arranged on the carrier 151, each of the N-LEDs 102 comprising a die 112 having a second surface area, SA2, wherein the SA2 has a largest spatial extent, SE2, that is greater than or equal to 300 micrometers.
[0039] Note that where reference is made to surface area, this relates to the epitaxial or epitaxy (in short ‘epi’) surface area of the die which may only be on the top surface of the die.
[0040] The M-LEDs 101 are configured to emit first light, LG1, having a first emission peak wavelength, I, in a wavelength range of red R, light. The N-LEDs 102 are configured to emit second light, LG2, having a second emission peak wavelength, X2, in a wavelength range that is shorter than the wavelength range of the first light emitted by the M- LEDs 101. A ratio, Rl, defined by SA2 / SA1 is equal to or larger than 10 and the arrangement light is white light having a correlated color temperature, CCT, in a range from 2000K to 6500K and a color rendering index, CRI, of at least 80.
[0041] For example, the M-LEDs 101 may comprise R LEDs and the N-LEDs 102 comprise one or more blue, B, LEDs emitting blue light having the second emission peak wavelength, X2, in a wavelength range 420-490 nm and one or more green, G, LEDs emitting green light having the second emission peak wavelength, X2, in a wavelength range 510-580 nm.
[0042] In such examples, the N-LEDs may further comprise one or more phosphor converted white LEDs.
[0043] In some embodiments, the number of R M-LEDs lOlmay be greater than or equal to 2 times the number of B N-LEDs 102 and the number of R M-LEDs 101 greater than or equal to 2 times the number of G N-LEDs 102.
[0044] In some embodiments, each N-LED 102 is neighbored by at least 2 R M-LEDs 101, preferably at least 3 R M-LEDs 101.
[0045] In some embodiments, and as schematically illustrated in figure 1c, each N- LED 102 may comprise 4 sides, wherein each side is neighbored by at least 1 R M-LED 101.
[0046] In some embodiments of the lighting arrangement 100, SEI is less than or equal to 80 micrometers, SE2 is greater than or equal to 500 micrometers and Rl is greater than or equal to 20. Although the lighting arrangement 100 schematically illustrated in figure la comprises a specific number of LEDs, i.e.16 N-LEDs and 64 M-LEDs, the number of M- LEDs of the plurality of M-LEDs (101) may be X and the number of N-LEDs of the plurality of N-LEDs 102 may be Y and wherein X is greater than or equal to 5 times Y.
[0047] As illustrated in figure la, the plurality of M-LEDs 101 may be homogeneously distributed with a first pitch, Pl, within a first region 161 on the carrier 151 and the plurality of N-LEDs 102 may be homogeneously distributed with a second pitch, P2, within a second region 162 on the carrier 151. The second region 162 may at least partly be overlapping the first region 161 and P2 may be greater than or equal to 2 times PL
[0048] As illustrated in figure 1c, the M-LEDs 101 and the N-LEDs 102 may have other shapes than the round shape exemplified in figure la. For example, as illustrated in figure 1c where the M-LEDs 101 and the N-LEDs 102 have rectangular shapes. For example, each of the M-LEDs 101 may have a first length, LI, a first width, Wl, and a first aspect ratio, ARI, defined by Ll / Wl. Each of the N-LEDs 102 may have a second length, L2, a second width, W2, and a second aspect ratio, AR2, defined by L2 / W2, and AR2 may be greater than ARI .
[0049] The dies 111 of the M-LEDs 101 may be free from any luminescent material; and the N-LEDs 102 may comprises a wavelength converter 160 as exemplified in figure lb. The dies 112 of the N-LEDs 102 are thus covered by the wavelength converter 160 comprising a luminescent material configured to at least partly convert second LED light emitted by said plurality of N-LEDs 102 into converted light.
[0050] Turning now to figure Id, in some embodiments, the plurality of M-LEDs 101 may be connected with a respective anode 121 having an anode surface area, ASA1, and a respective cathode 122 having a cathode surface area, CSA1. Similarly, the plurality of N- LEDs 102 may be connected with a respective anode 131 having an anode surface area, ASA2, and a respective cathode 132 having a cathode surface area, CSA2. In some embodiments, ASA2 may be greater than or equal to 4 times ASA1 and / or CSA2 may be greater than or equal to 4 times CSA1.
[0051] As schematically illustrated in figure le, the plurality of M-LEDs 101 may be connected via a first circuitry 141 and the plurality of N-LEDs 102 may be connected via a second circuitry 142. The lighting arrangement 100 may comprise a controller 140 configured to individually control the emission of the first light emitted by said plurality of M-LEDs 101 via the first circuitry 141 and the emission of the second light emitted by said plurality of N-LEDs 102 via the second circuitry 142. For example, as illustrated in figure If, the first circuitry 141 may comprise a first number of parallel arrangements PAI and the second circuitry 142 may comprise a second number of parallel arrangements PA2, PAI being greater than PA2.
[0052] A lamp 200, or a luminaire 200, comprising a lighting arrangement 100 is schematically illustrated in figure 2. Such a lamp 200 or luminaire 200 may comprise a housing 201 and a transparent cover 202.
Claims
CLAIMS:
1. A lighting arrangement (100) configured to provide arrangement light, comprising; a carrier (151), a plurality of first light emitting diodes, M-LEDs, (101) arranged on said carrier (151), each of the M-LEDs (101) comprising a die (111) having a first surface area SAI, the first surface area, SAI, having a largest spatial extent, SEI, that is less than or equal to 100 micrometers, a plurality of second light emitting diodes, N-LEDs (102) arranged on said carrier (151), each of the N-LEDs (102) comprising a die (112) having a second surface area SA2, the second surface area, SA2, having a largest spatial extent, SE2, that is greater than or equal to 300 micrometers, and wherein: the M-LEDs (101) are configured to emit first light, LG1, having a first emission peak wavelength, I, in a wavelength range 600-780 nm of red, R, light, the N-LEDs (102) are configured to emit second light, LG2, having a second emission peak wavelength, X2, in a wavelength range that is shorter than the wavelength range of the first light emitted by the M-LEDs (101), wherein the number of M-LEDs of the plurality of M-LEDs (101) is X, the number of N-LEDs of the plurality of N-LEDs (102) is Y, and X is greater than or equal to 5 times Y, and wherein a ratio, Rl, defined by SA2 / SA1 is equal to or larger than 10; and said arrangement light is white light having a correlated color temperature, CCT, in a range from 2000K to 6500K and a color rendering index, CRI, of at least 80.
2. The lighting arrangement (100) according to claim 1, wherein:SEI is less than or equal to 80 micrometers;SE2 is greater than or equal to 500 micrometers; andRl is greater than or equal to 20.
3. The lighting arrangement (100) according to any one of the preceding claims, wherein the N-LEDs (102) comprise one or more blue, B, LEDs having the second emission peak wavelength, 2, in a wavelength range 420-490 nm and one or more green, G, LEDs having the second emission peak wavelength, 2, in a wavelength range 510-580 nm.
4. The lighting arrangement (100) according to any one of the preceding claims, wherein: the plurality of M-LEDs (101) are homogeneously distributed with a first pitch, Pl, within a first region (161) on the carrier (151), the plurality of N-LEDs (102) are homogeneously distributed with a second pitch, P2, within a second region (162) on the carrier (151), the second region (162) at least partly overlapping the first region (161), and wherein P2 is greater than or equal to 2 times PL5. The lighting arrangement (100) according to any one of the preceding claims, wherein: each of the M-LEDs (101) has a first length, LI, a first width, Wl, and a first aspect ratio, ARI, defined by Ll / Wl, each of the N-LEDs (102) has a second length, L2, a second width, W2, and a second aspect ratio, AR2, defined by L2 / W2, and wherein AR2 is greater than ARI .
6. The lighting arrangement (100) according to any one of the preceding claims, wherein: the dies of the M-LEDs (101) are free from any luminescent material; and the dies of the N-LEDs (102) are covered by a wavelength converter (160) comprising a luminescent material configured to at least partly convert second LED light emitted by said plurality of N-LEDs (102) into converted light.
7. The lighting arrangement (100) according to any of the claims 3-6, wherein the N-LEDs (102) further comprises one or more phosphor converted white LEDs.
8. The lighting arrangement (100) according to any one of claims 3-7, wherein: the number of R M-LEDs (101) is greater than or equal to 2 times the numberof B N-LEDs (102), and the number of R M-LEDs (101) is greater than or equal to 2 times the number of G N-LEDs (102).
9. The lighting arrangement (100) according to any one of claims 3-8, where: each N-LED (102) is neighbored by at least 2 R M-LEDs (101), preferably at least 3 R M-LEDs (101).
10. The lighting arrangement (100) according to any one of the preceding claims, wherein each N-LED (102) comprises 4 sides, wherein each side is neighbored by at least 1 R M-LED (101).
11. The lighting arrangement (100) according to any one of the preceding claims , wherein: the plurality of M-LEDs (101) are connected with a respective anode (121) having an anode surface area, ASA1, and a respective cathode (122) having a cathode surface area, CSA1, the plurality of N-LEDs (102) are connected with a respective anode (131) having an anode surface area, ASA2, and a respective cathode (132) having a cathode surface area, CSA2, and whereASA2 is greater than or equal to 4 times ASA1 and / or CSA2 is greater than or equal to 4 times CSA1.
12. The lighting arrangement (100) according to any one of the preceding claims, wherein: the plurality of M-LEDs (101) are connected via a first circuitry (121), the plurality of N-LEDs (102) are connected via a second circuitry (122), and wherein: the lighting arrangement (100) comprises a controller (140) configured to individually control the emission of the first light emitted by said plurality of M-LEDs (101) via the first circuitry (121) and the emission of the second light emitted by said plurality of N-LEDs (102) via the second circuitry (122).
13. The lighting arrangement (100) of claim 11, wherein: the first circuitry (121) comprises a first number of parallel arrangements, PAI, the second circuitry (122) comprises a second number of parallel arrangements, PA2, andPAI is greater than PA2.
14. A lamp (200) or a luminaire (200) comprising the lighting arrangement (100) according to any one of the preceding claims.