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EP-4736237-A1 - LIGHTING ARRANGEMENT

EP4736237A1EP 4736237 A1EP4736237 A1EP 4736237A1EP-4736237-A1

Abstract

A lighting arrangement comprises a respective plurality of first and second light emitting diodes M-LEDs, N-LEDs, arranged on a carrier. Each of the M-LEDs comprising a die having a first surface area SA1 with a largest spatial extent SE1 of at most 100 micrometers. The N-LEDs are arranged on the carrier, each of the N-LEDs comprising a die having a second surface area SA2 with a largest spatial extent SE2 of at most 300 micrometers. The M-LEDs are configured to emit first light having a first emission peak wavelength in red light. The N-LEDs are configured to emit second light having a second emission peak of a shorter wavelength. A ratio 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 2000-6500K and a color rendering index of at least 80.

Inventors

  • VAN BOMMEL, TIES

Assignees

  • Signify Holding B.V.

Dates

Publication Date
20260506
Application Date
20240624

Claims (14)

  1. 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. 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; and Rl is greater than or equal to 20.
  3. 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. 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 PL
  5. 5. 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. 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. 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. 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 number of 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. 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. 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. 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 where ASA2 is greater than or equal to 4 times ASA1 and/or CSA2 is greater than or equal to 4 times CSA1.
  12. 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. 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, and PAI is greater than PA2.
  14. 14. A lamp (200) or a luminaire (200) comprising the lighting arrangement (100) according to any one of the preceding claims.

Description

Lighting arrangement FIELD OF THE INVENTION 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). BACKGROUND OF THE INVENTION 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 SUMMARY OF THE INVENTION It is of interest to provide a lighting arrangement that overcomes drawbacks of the prior art as discussed above. 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. 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. 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. Red light is in the wavelength range 600nm to 780nm. Near red light is in the wavelength range 600nm to 680nm. 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. 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. 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. 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. 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 li