Lighting device with ceramic garnet

Patent metadata

Field	Value
Publication number	US-10969670-B2
Application number	US-201515525848-A
Country	US
Kind code	B2
Filing date	Nov 4, 2015
Priority date	Nov 11, 2014
Publication date	Apr 6, 2021
Grant date	Apr 6, 2021

Abstract

The invention provides a lighting device comprising a plurality of solid state light sources and an elongated ceramic body having a first face and a second face defining a length (L) of the elongated ceramic body, the elongated ceramic body comprising one or more radiation input faces and a radiation exit window, wherein the second face comprises the radiation exit window, wherein the plurality of solid state light sources are configured to provide blue light source light to the one or more radiation input faces and are configured to provide to at least one of the radiation input faces a photon flux of at least 1.0*1017 photons/(s·mm2), wherein the elongated ceramic body comprises a ceramic material configured to wavelength convert at least part of the blue light source light into at least converter light, wherein the ceramic material comprises an A3B5O12:Ce3+ ceramic material, wherein A comprises one or more of yttrium (Y), gadolinium (Gd) and lutetium (Lu), and wherein B comprises aluminum (Al).

First claim

The invention claimed is:

1. A lighting device comprising a plurality of solid state light sources and an elongated ceramic body having a first face and a second face and a length (L) of the elongated ceramic body, the elongated ceramic body comprising one or more radiation input faces and a radiation exit window, the second face comprising the radiation exit window, the plurality of solid state light sources configured to provide blue light source light to the one or more radiation input faces and configured to provide to at least one of the radiation input faces a photon flux of at least 1.0*10 17 photons/(s·mm 2 ), the elongated ceramic body comprising a ceramic material configured to wavelength convert at least part of the blue light source light into converter light, the ceramic material comprising an A 3 B 5 O 12 :Ce 3+ ceramic material, A comprising one or more of yttrium (Y), or gadolinium (Gd) or lutetium (Lu), B comprising aluminum (Al), the elongated ceramic body having a maximum thermo luminescence intensity between 50° C. and 100° C. at most 10 times higher than a maximum thermo luminescence intensity between 50° C. and 100° C. of a single crystal with the same A 3 B 5 O 12 :Ce 3+ composition as the elongated ceramic body.

2. The lighting device of claim 1 , wherein the elongated ceramic body is obtained by performing a vacuum sintering process and an isostatic pressing process at elevated temperatures of starting material in a neutral or reducing atmosphere, followed by the annealing process.

3. The lighting device of claim 1 , further comprising an optical reflector configured upstream of the radiation exit window, wherein the optical reflector is configured to reflect light back into the elongated ceramic body, wherein the radiation exit window is configured perpendicular to the one or more radiation input faces, and wherein the lighting device further comprises an optical filter configured downstream of the radiation exit window and configured to reduce a relative contribution of one or more of non-green and non-red light in the converter light.

4. The lighting device of claim 1 , wherein the length (L) is at least 20 mm, wherein a concentration of cerium is in a range of about 0.1% to about 3.0% of A, and wherein the photon flux is at least 4.5*10 17 photons/(s·mm 2 ).

5. The lighting device of claim 4 , having a lumen output of the converter light downstream from the radiation exit window, wherein at a fixed photon flux per mm 2 the device is configured so that the lumen output is scalable with the length (L) of the elongated ceramic body at least within a length (L) range of about 20 mm to about 00 mm.

6. The lighting device of claim 1 , wherein, in a first option, A in the ceramic material comprises at least 90% Lu, or wherein, in a second option, A in the ceramic material comprises about 50% to about 95% Y and comprises about 5% to about 50% Gd, and wherein in both the first option and in the second option, B in the ceramic material comprises at least 95% Al and Ga.

7. The lighting device of claim 1 , wherein the elongated ceramic body comprises a geometrical concentration factor, defined as a ratio of the radiation input faces area to the radiation exit window area, of at least 2.

8. A method for production of an elongated ceramic body, the elongated ceramic body comprising one or more radiation input faces and a radiation exit window, the elongated ceramic body configured to receive, at least one of the radiation input faces, a photon flux of at least 1.0*10 17 photons/(s·mm 2 ) and the elongated ceramic body comprising a ceramic material configured to wavelength convert at least part of a blue light source light into at least converter light, the ceramic material comprising an A 3 B 5 O 12 :Ce 3+ ceramic material, A comprising one or more of yttrium, gadolinium and lutetium, B comprising aluminum, the method comprising processing starting material at elevated temperatures to provide the elongated ceramic body, and annealing the elongated ceramic body in an annealing process in an oxidizing atmosphere with less than 100,000 ppm O 2 at a temperature of at least 1000° C.

9. The method of claim 8 , wherein the method comprises processing starting material at elevated temperatures, a vacuum sintering process, and an isostatic pressing process.

10. The method of claim 8 , wherein processing the starting material at elevated temperatures is performed in a neutral or reducing atmosphere.

11. The method of claim 8 , wherein the starting material is chosen such that, in a first option, A in the ceramic material comprises at least 90% Lu, or, in a second option, such that A in the ceramic material comprises in a range of about 50% Y to about 95% Y and in a range of about 5% Gd to about 50% Gd, and wherein in both the first option, and in the second option, B in the ceramic material comprises at least 95% Al and Ga.

Assignees

• Koninklijke Philips Nv

Inventors

• Ronda Cornelis Reinder
• Boerekamp Jacobus Gerardus
• Jagt Hendrik Johannes Boudewijn

Classifications

• C09K11/7774

  Aluminates · CPC title

• C04B2235/6584

  at an oxygen percentage below that of air · CPC title

• C04B2235/95

  Products characterised by their size, e.g. microceramics · CPC title

• C04B2235/6581

  Total pressure below 1 atmosphere, e.g. vacuum · CPC title

• C04B2235/664

  Reductive annealing · CPC title