Illumination assembly

Abstract

The present invention relates to an illumination assembly comprising a specific combination of one or more white LEDs and one or more red-orange LEDs with improved spectral characteristics (e.g., specific color performance characteristics, such as a desirable color rendering index and color temperature).

Claims

1. An illumination assembly capable of emitting an output light comprising: a housing; and a light source being two different types of LEDs, wherein one type of LED is one or more white LEDs emitting a first light along a first path and the other type of LED is one or more red-orange LEDs emitting a second light along a second path, wherein the one or more white LEDs and the one or more red-orange LEDs are mounted in the housing such that the first light and the second light are mixed to form the output light transmitted along a third path or to form the output light at a field position, wherein the colour rendering index Ra of the output light is 85 or more and the colour rendering index R9 of the output light is 85 or more, wherein the one or more white LEDs and one or more red-orange LEDs are provided in an array, wherein the array is a plurality of discrete first and second clusters.

2. An illumination assembly as claimed in claim 1 wherein each of the one or more white LEDs is a cold white LED.

3. An illumination assembly as claimed in claim 1 or 2 wherein the white LEDs have a correlated colour temperature in the range 5000-7000K.

4. An illumination assembly as claimed in claim 1 wherein the chromaticity coordinate (X) of each of the one or more white LEDs is in the range 0.300 to 0.350.

5. An illumination assembly as claimed in claim 1 wherein the chromaticity coordinate (Y) of each of the one or more white LEDs is in the range 0.310 to 0.375.

6. An illumination assembly as claimed in claim 1 wherein each of the one or more white LEDs is a LUXEON white LED selected from the group consisting of bin WN, UN, UO, WO, XN, XO and VN.

7. An illumination assembly as claimed in claim 6 wherein each of the one or more white LEDs is a LUXEON white LED selected from the group consisting of bin WO or WN.

8. An illumination assembly as claimed in claim 1 wherein each of the one or more red-orange LEDs has a dominant wavelength in the range 613 to 621 nm.

9. An illumination assembly as claimed in claim 1 wherein the colour rendering index Ra of the output light is 90 or more.

10. An illumination assembly as claimed in claim 1 wherein the colour rendering index R9 of the output light is 90 or more.

11. An illumination assembly as claimed in claim 1 wherein the output light has a correlated colour temperature in the range 4000 to 4600 K.

12. An illumination assembly as claimed in claim 1 wherein each first cluster is a cluster of narrow beam LEDs and each second cluster is a cluster of broad beam LEDs.

13. An illumination assembly as claimed in claim 1 wherein the beam size of the output light from the first cluster is narrower than the beam size of the output light from the second cluster.

14. An illumination assembly as claimed in claim 12 or 13 wherein the difference between the beam size of the output light from the first cluster and the beam size of the output light from the second cluster is variable.

15. An illumination assembly as claimed in claim 12 or 13 wherein the intensity of the output light from the first cluster is variable relative to the intensity of the output light from the second cluster.

16. An illumination assembly as claimed in claim 1 wherein each first cluster and each second cluster is a cluster of narrow beam LEDs and broad beam LEDs.

17. An illumination assembly as claimed in claim 16 wherein the intensity of the output light from the first cluster is variable relative to the intensity of the output light from the second cluster.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will now be described in a non-limitative sense with reference to examples and to the accompanying FIGS. in which:

(2) FIG. 1: A first embodiment of the illumination assembly of the invention shown schematically in cross-section;

(3) FIGS. 2A to 2D: A plan view of a second, third, fourth and fifth embodiment of the illumination assembly of the invention;

(4) FIG. 3: A sixth embodiment of the illumination assembly of the invention shown schematically in cross-section;

(5) FIG. 4: A plan view of a seventh embodiment of the illumination assembly of the invention; and

(6) FIG. 5: An eighth embodiment of the illumination assembly of the invention shown schematically in cross-section.

DETAILED DESCRIPTION OF THE INVENTION

(7) A first embodiment of the illumination assembly of the invention 1 is illustrated schematically in cross-section in FIG. 1. One or more white LEDs and one or more red-orange LEDs 2 on a printed circuit board 3 are mounted in a housing (not shown). To the rear of the printed circuit board 3 is a heat sink 4. Each LED 2 is equipped with a beam shaping reflector 5. Light from the white and red-orange LEDs passes through a wedge lens 7 which converges and mixes the light beam into an output light to a spot.

(8) FIGS. 2A to 2C illustrate in plan view second, third and fourth embodiments of the illumination assembly of the invention with a similar arrangement of parts to that of FIG. 1 described above. In these embodiments, narrow beam and wide beam white LEDs and red-orange LEDs are disposed in an array of hexagonal clusters. In each hexagonal cluster, a red-orange LED sits at the centre of the white LEDs.

(9) In the second embodiment (FIG. 2A), hexagonal clusters 6 of narrow beam red-orange LEDs and white LEDs (shaded) and hexagonal clusters 7 of wide beam white LEDs and red-orange LEDs (unshaded) are disposed in a hexagonal array which is capable of solid state focusing. A red-orange LED lies at the centre of each cluster.

(10) In the third embodiment (FIG. 2B), hexagonal clusters 8 of alternating narrow beam (shaded) and wide beam (unshaded) white and red-orange LEDs are in a hexagonal array which is capable of solid state focussing. A red-orange LED lies at the centre of each cluster.

(11) In the fourth embodiment (FIG. 2C), hexagonal clusters 9 of narrow beam (unshaded) white and red-orange LEDs are in a triangular array which is incapable of solid state focussing. A red-orange LED lies at the centre of each cluster.

(12) FIG. 2D illustrates in plan view a fifth embodiment with a similar arrangement of parts to that of FIG. 1 described above or FIG. 3 described below. In this embodiment, white LEDs and red-orange LEDs are disposed in a complex array.

(13) A sixth embodiment of the assembly of the invention 61 is illustrated schematically in cross-section in FIG. 3. One or more white LEDs and one or more red-orange LEDs 62 are mounted in a housing (not shown). Each LED 62 is positioned at a first focal point of an ellipsoidal reflector 65 which re-images the LED to the second focus of the ellipsoidal reflector 65 which is approximately in the same plane as an array of apertures 66. This second focus is then re-imaged by an array of lenses 67 to the field of interest (0.5-1 m away). Mixed light from the white and red-orange LEDs 62 passes through a converging Fresnel lens 69 which converges the light into an output light beam focussed onto a spot. By mechanically moving the array of lenses 67 the spot size at the field position can be adjusted. This gives a mechanical means for adjusting the beam size.

(14) FIG. 4 illustrates in plan view a seventh embodiment with a similar arrangement of parts to that of FIGS. 1 and 2 described above. White LEDs and red-orange LEDs are disposed in a honeycomb array with varying beam sizes (as denoted) to permit solid state focussing.

(15) An eighth embodiment of the illumination assembly of the invention 961 is illustrated schematically in cross-section in FIG. 5. One or more white LEDs and one or more red-orange LEDs 962 are mounted in a housing (not shown). Each LED 962 is positioned at a first focal point of an ellipsoidal reflector 965 which re-images the LED to the second focus of the ellipsoidal reflector 965 which is approximately in the same plane as an array of apertures 966. This second focus is then re-imaged by an array of lenses 967 to the field of interest (0.5-1 m away). Mixed light from the white and red-orange LEDs 962 passes through a converging Fresnel lens 969 which converges the light into an output light beam focussed onto a spot. By mechanically moving the array of lenses 967, the spot size at the field position can be adjusted. This gives a mechanical means for adjusting the beam size.

EXAMPLE

(16) TABLE-US-00001 TABLE 1 Measured colour parameters from light generated using white LEDs and red-orange LEDs. White bin Peak CRI CCT R9 VN 91.1 3502 89.8 WO 89.9 4368 93.4 WN 94.4 4280 94.2 XO 90 5181 86.7 XN 90.5 5416 90.5

(17) The colour rendering index R9 and correlated colour temperature of combinations of red-orange LUXEON LEDs with various white LUXEON LEDs were measured (see Table 1). The net effect of the presence of the red-orange LED on the white LEDs is that the colour rendition of the source is improved at a particular correlated colour temperature.

(18) The light produced by the combination of the white LEDS from bins WN and WO and the red-orange LED has almost ideal characteristics for medical lighting, i.e., it has an excellent colour rendering index (high R9 and Ra) at a desirable correlated colour temperature of about 4300K.

(19) The light produced by the combination of the white LEDS from bin VN and the red-orange LED has a lower correlated colour temperature with excellent colour rendition. This is an ideal light source for room lighting.

(20) The light produced by the combination of the white LEDS from bins XO or XN and the red-orange LED has a higher colour temperature with excellent colour rendition. This creates a good match to midday daylight.