Light delivery device with improved conversion element

FIELD OF THE INVENTION

This invention relates to the field of light delivery devices, especially light delivery devices which are used for medical purposes, such as endoscopy. BACKGROUND OF THE INVENTION In endoscopy devices, light is delivered to a body lumen or body cavity, e.g. for diagnostic purposes as well as photodynamic therapy of atherosclerosis, malignant or benign tumor tissue, cancerous cells and other medical treatments. Devices of the prior art are disclosed in e.g. the US 2005/0165462, which is incorporated herein by reference. Especially in endoscopy devices, which are used for diagnosis, a light source with a high flux density is used, such as Xenon lamps and halogen lamps. However, in prior art applications there is no possibility to change the color temperature of the light without deterioration of the light flux and/or light density. The term 'color temperature' is used in lieu of the definition of the correlated color temperature of a light source.

For example in halogen lamps it is possible to decrease the color temperature (increase the red emission relative to green and blue) by simply diminishing the light flux, but a shift towards the red while maintaining the light flux is impossible. Such a change in color temperature on the other hand would allow a further facilitation of the diagnosis since it is known that e.g. by changing the color temperature the different tissues inside a patient's body, which is subjected to the endoscopy, appear differently on the picture made by the endoscopy camera. Therefore, it would be possible to improve the diagnosis by simply changing the color temperature and/or the spectral composition of the illumination.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a light delivery device, especially a light delivery device for medical purposes, which allows a change in color temperature while essentially maintaining or even improving the light flux and/or light density.

This object is achieved by a light-emitting device having the features of Claim 1. Accordingly, a light delivery device, especially for medical lighting purposes, is provided comprising at least one light emitting device comprising at least one first LED which emits light in the wavelength range of >220 nm to <550 nm and at least one conversion element placed towards the at least one first LED, which converts at least partly the light from the at least one first LED to light in the wavelength range of >300 nm to ≤IOOO nm, where the at least one conversion element comprises a ceramic conversion material. By doing so, it is possible to realize a light delivery device which for most applications in the present invention has one or more of the following advantages:

Due to the ceramic conversion material, a high light flux density can be achieved, allowing the use of the light delivery device in a broad variety of applications, especially for endoscopical devices - Due to the ceramic conversion material it is possible to change the color temperature of the light delivery device especially towards the "red" without a deterioration in light flux.

Due to the ceramic conversion material it is possible to increase the light flux without changing the geometrical properties of light generation and emission, maintaining the efficiency of any light collection optics.

According to the invention, the light-emitting device comprises at least one first LED which emits light in the wavelength range of >220 nm and ≤IOOO nm. LEDs with an emittance in this wavelength range have proven themselves in practice.

Preferably, those LEDs consist of a AlInGaN electroluminescent device with a phosphor conversion element attached, absorbing at least partially LED emitted light and reemit that light at a wavelength larger than the LED emission wavelength.

According to a preferred embodiment of the present invention, the light

emitting device comprises at least one first LED which emits light in the wavelength range of >250 nm and <800 nm, more preferably >300 nm and <780 nm.

The term "ceramic material" in the sense of the present invention means especially a crystalline or polycrystalline compact material or composite material with a controlled amount of pores or which is porefree.

The term "polycrystalline material" in the sense of the present invention means especially a material with a volume density larger than 90 percent of the main constituent, consisting of more than 80 percent of single crystal domains, with each domain being larger than 0.5 μm in diameter and having different crystallographic orientations. The single crystal domains may be connected by amorphous or glassy material or by additional crystalline constituents.

According to a preferred embodiment of the present invention, the at least one conversion element has a refractive index n of >1.5 and <3 and the ratio A:E is >2: 1 and <50000:l, where A and E are defined as follows: - the at least one conversion element comprises at least one entrance surface where light emitted by the at least one LED can enter the conversion element, and at least one exit surface, where light can exit the at least one conversion element, each of the at least one entrance surfaces having an entrance surface area, the entrance surface area(s) being numbered Ai ... A _n and each of the at least one exit surfaces having an exit surface area, the exit surface area(s) being numbered Ei ... E _n and the sum of each of the at least one entrance surface areas A being A = Ai +A ₂ ... + A _n and the sum of each of the at least one exit surface areas E being E = Ei +E ₂ ... +E _n By doing so, it is possible for most applications within the present invention to realize a lamp combining a high light flux with a greatly increased luminance compared to the LED.

According to a preferred embodiment of the invention, the light emitting device comprises at least one conversion element which comprises at least one entrance surface A where light emitted by the at least one LED can enter the conversion element. After absorption, light reemitted by the conversion element can leave through the entrance surface only with the fraction emitted within the escape cone of the material.

The main fraction of the emitted light will be trapped within the conversion element and guided to an exit surface by total internal reflection.

In order to enhance this process, this at least one entrance surface has according to a preferred embodiment of the present invention a roughness Ra of >1 nm and <500 nm, preferably >10 nm and <100 nm and more preferably >20 nm and <40 nm. By this effect it is possible indeed to concentrate light at the exit surface E of the light conversion element.

According to a preferred embodiment of the present invention, the LEDs are in direct contact with the conversion elements but each have a lower refractive index than the conversion elements.

However, according to another preferred embodiment of the present invention, the LEDs and the conversion elements are placed at a distance from each other. In this case, preferably, the distance between the conversion elements and the LEDs is > 1 μm and < 100 mm, preferably >100 μm and <10 mm and more preferably >l mm and ≤5 mm.

Besides the optical function of the separation of the LEDs and the conversion layer it is also advantageous and, insofar a further preferred embodiment of the present invention is concerned, to have a thermal decoupling of the conversion layer and the LEDs. In most applications, the efficiency of the conversion process decreases significantly for temperatures well above 100 ⁰ C. In another preferred embodiment of this invention special cooling means are applied to the light-emitting device to dissipate heat generated within the conversion layer and the LED(s) to a heat sink outside the device, the LED(s) and the conversion element(s) being placed at a distance from each other preferably as described above. This cooling can be realized by forced air blowing and/or by liquid cooling, pumping a liquid around the conversion layer. In this preferred embodiment of the present invention the cooling means is therefore a liquid, preferably selected from a group comprising Water-, Oils, Propylene-, Ethylene-, Glycol based systems and mixtures thereof. In the latter case the refractive index of the liquid should be as low as possible to prevent light extraction of emitted light through the surface A of the conversion layer. The difference of the refractive index of the conversion layer ric and the liquid ni should be O.l ≤ ric - ni < 3, preferably 0.3 < nc - ni < 2.5 and more preferably 0.5 < n _o - ni < 2.

According to the invention, the light that enters the conversion element is at least partly converted to light in the wavelength range of >300 nm and ≤IOOO nm. By doing so, the light emitting device will emit light in a wavelength range, which is suitable for a broad variety of applications. According to a preferred embodiment of the present invention, the light that enters the conversion element is at least partly converted to light in the wavelength range of >350 nm and <880 nm, more preferably >380 nm and <780 nm.

According to a preferred embodiment of the invention, the conversion element comprises at least one exit surface, where light can exit the conversion element. In order to enhance this, according to a preferred embodiment of the present invention, the at least one exit surface is equipped with a refractive and/or diffractive structure or surface. This includes that the at least one exit surface is equipped with a scattering structure, a pyramide-like structure, a micro lens structure or a compound parabolic concentrator (CPC). The exit surface may contain one or a plurality of the indicated structures. The geometry of the exit structure can also be used to direct the emitted light from the exit surface to meet any requirement of an application.

According to a preferred embodiment of the invention, the at least one exit surface is optically directly coupled to a light guiding structure, by coupling the light conversion element to a light guide with a medium having an refractive index n _c close to the refractive index of either the conversion element n _cOnv or the light guide n _g . The minimum of the difference of (absOvricαnv) and abs(nc-n _g ) is preferably < 0.3, more preferably < 0.1 and most preferably < 0.01.

According to a preferred embodiment of the invention, each of the at least one entrance surfaces has an entrance surface area, the entrance surface areas being numbered Ai ... A _n and each of the at least one exit surfaces has an exit surface area, the exit surface areas being numbered Ei ... E _n and the sum of each of the at least one entrance surface areas A _n is A = Ai +A ₂ ... + A _n and the sum of each of the at least one exit surface areas E _n is E = Ei +E ₂ ... +E _n and the ratio A:E, A and E being as defined above, is >2:1 and <50000:l. By doing so, the light flux of the LED can be set within the preferred and desired range. According to a preferred embodiment of the present invention, the ratio A:E, A and E being as defined above, is >5:1 and <5000:l, more preferably >10:l and

<3000:l yet more preferably >20:l and ≤1000:l, and most preferably >50:l and <500:l.

According to a preferred embodiment of the invention, the at least one conversion element has an refractive index n of >1,5 and <3. By doing so, it can be easily achieved that the efficiency of the LED is within a desired range. Especially, by setting the refractive index as described, the light that enters the conversion element as described will undergo total reflection at the sides/surfaces of the conversion element, which are no exit surfaces. The fraction of the light from the LEDs which is emitted through the exit surface (possibly after conversion) of the conversion element compared to the total emitted light can be as high as

^{1 -} 2tf ' with n being the refractive index of the conversion element. This results in a very highly efficient light-emitting device. Preferably the at least one conversion element has a refractive index n of >1.5 and <2.8, more preferably >1.7 and <2.6 According to a preferred embodiment of the present invention, the transmittance for emitted light of the conversion element is >0.8 and <1. This greatly enhances the efficiency of the light-emitting device. Preferably, the transmittance of the conversion element is >0.9 and <1, more preferably >0.95 and <1.

According to a preferred embodiment of the present invention, the relation of the quantum efficiency at a temperature T compared to the quantum efficiency at 20 ⁰ C (thermal quenching) of the conversion element is >70% and <100% at 100 ⁰ C, preferably >80% and <100% at 100 ⁰ C and most preferably >90% and <100% at 100 ⁰ C.

According to a preferred embodiment of the present invention, the temperature at which the quantum efficiency of the conversion layer is reduced to 50% compared to the quantum efficiency at room temperature, (= TQ ₅₀ % -value), is >120°C and <300°C, preferably 150 ⁰ C < TQ ₅₀ % < 350 ⁰ C and more preferably 180 ⁰ C < TQ ₅₀ % < 400 ⁰ C.

According to a preferred embodiment of the present invention, the light delivery device comprises at least one further auxiliary LED which emits in the wavelength of >220 nm to <600 nm.

By doing so, it is possible in most applications within the present invention to very easily shift the color temperature of the light provided by the light delivery device without lowering the original light flux.

According to a preferred embodiment of the present invention, the auxiliary LEDs have (combined) a power of >2% to <100% of the first LED. In case that more than one first LED is present, it is preferred that the auxiliary LEDs have (combined) a power of >10% to <1000% of the combined first LEDs.

According to a preferred embodiment of the present invention, the auxiliary LEDs are mounted either individually or in a die package on a single supporting plate serving as a heat conductor and providing the electrical contacts for operation. The one or more supporting plates may also contain active electronic elements for LED protection, operation and control. In addition, according to a preferred embodiment of the present invention the auxiliary LEDs on a supporting plate are covered with optical structures to optimise the light output of the auxiliary LEDs. In a further preferred embodiment of the present invention, the auxiliary

LEDs are mounted on a supporting plate with a packing density of > 0.05 and < 0.5, preferably > 0.1 and < 0.3. The packing density is the ratio of the sum of the LED die surface areas divided by the surface area of the supporting plate. By doing so, it is possible to realize a light emitting device with particularly high lumen flux and superior luminance at a high power efficiency, which is achieved by effective cooling of the auxiliary LEDs, keeping the junction temperature below the specified values of the auxiliary LEDs.

According to a preferred embodiment of the present invention, the light from the at least one first LED is sent to the at least one conversion element in a preferred first light propagation direction and the light sent from the auxiliary LEDs towards the at least one conversion element has an angle towards the preferred first light direction of > 65° and < 115°, preferably > 75° and < 105° and most preferably > 85° and < 95°.

In such an arrangement it is possible in most applications within the present invention to ensure that the light that is emitted by the auxiliary LEDs is only or essentially used for conversion inside the conversion element, thereby allowing to "add" light of a certain wavelength.

According to a preferred embodiment of the present invention, the auxiliary LEDs are placed inside a support tube.

Preferably the part of the support tube, where no auxiliary LEDs are placed, is preferably covered with a highly reflective coating, preferably a mirror or a dielectric coating or a mixture thereof. By doing so, the efficiency of the conversion element(s) and the light emitting device can be enhanced further. The mirror is preferably applied by sputtering or evaporation in vacuum directly on the at least one further surface which is neither an exit nor an entrance surface. The mirror material is preferably selected from a group comprising silver, aluminum and/or mixtures thereof. The thickness of the mirror is preferably >50nm and < 1 OOOnm.

In such an arrangement it is possible in most applications within the present invention to ensure that the light that is emitted by the auxiliary LEDs is only or essentially used for conversion inside the conversion element, thereby allowing to "add" light of a certain wavelength and lowering the power requirements of the LEDs. According to a preferred embodiment of the invention, the glass phase ratio of the ceramic conversion material is >2 % to < 5 %, according to an embodiment of the present invention, >3 % to < 4 %. It has been shown in practice that materials with such a glass phase ratio show the improved characteristics, which are advantageous and desired for the present invention. The term "glass phase" in the sense of the present invention means especially non-crystalline grain boundary phases, which may be detected by scanning electron microscopy or transmission electron microscopy.

According to a preferred embodiment of the present invention, the surface roughness RMS (disruption of the planarity of a surface; measured as the geometric mean of the difference between highest and deepest surface features) of the surface(s) of the ceramic conversion material and/or the conversion element(s) is ≥O.OOl μm and <100 μm. According to one embodiment of the present invention, the surface roughness of the surface(s) of the ceramic conversion material and/or the conversion element(s) is ≥O.Ol μm and <10 μm, according to another embodiment of the present invention ≥O.l μm and <5 μm, according to yet another embodiment of the present invention >0.15 μm and <3 μm. and according to still another embodiment of the present invention >0.2 μm and < 2 μm.

According to a preferred embodiment of the present invention, the specific surface area of the ceramic conversion material and/or the conversion element(s) is >10 ^~7 m ² /g and ≤l m ² /g.

According to a preferred embodiment of the present invention, the ceramic conversion material is essentially made of material selected from the group of (M ^I i_ _x _ _y M ^π _x M ^m _y ) ₃ (M ^IV i_ _z M ^v _z )5θi2 - where M ¹ is selected from the group comprising Y, Lu or mixtures thereof, M ^π is selected from the group comprising Gd, La, Yb or mixtures thereof, M ^m is selected from the group comprising Tb, Pr, Ce, Er, Nd, Eu or mixtures thereof, M ^w is Al, M ^v is selected from the group comprising Ga, Sc or mixtures thereof, and O≤x≤ 1 , O≤y≤O .1 , O≤z≤ 1 ,

(M ^I i_ _x _ _y M ^π _x M ^m _y ) ₂ θ3 - where M ¹ is selected from the group comprising Y, Lu or mixtures thereof, M ^π is selected from the group comprising Gd, La, Yb or mixtures thereof, M ^m is selected from the group comprising Tb, Pr, Ce, Er, Nd, Eu, Bi, Sb or mixtures thereof, and O≤x≤l, O≤y≤O.1, (MV _x _ _y M ^π _x M ^m _y )Si_ _z Se _z - where M ¹ is selected from the group comprising

Ca, Sr, Mg, Ba or mixtures thereof, M ^π is selected from the group comprising Ce, Eu, Mn, Tb, Sm, Pr, Sb, Sn or mixtures thereof, M ^m is selected from the group comprising K, Na, Li, Rb, Zn or mixtures thereof, and O≤x≤O.Ol, 0≤y≤0.05, O≤z≤l,

(MV _x _ _y M ^π _x M ^m _y )O - where M ¹ is selected from the group comprising Ca, Sr, Mg, Ba or mixtures thereof, M ^π is selected from the group comprising Ce, Eu, Mn, Tb, Sm, Pr or mixtures thereof, M ^m is selected from the group comprising K, Na, Li, Rb, Zn or mixtures thereof, and O≤x≤O.1 , O≤y≤O.1 , - where M ¹ is selected from the group comprising La, Y, Gd, Lu, Ba, Sr or mixtures thereof, M ^π is selected from the group comprising Eu, Tb, Pr, Ce, Nd, Sm, Tm or mixtures thereof, M ^m is selected from the group comprising Hf, Zr, Ti, Ta, Nb or mixtures thereof, and O≤x≤l,

(M ^I i_ _x M ^π _x M ^m i_ _y M ^Iv _y )θ3 - where M ¹ is selected from the group comprising Ba, Sr, Ca, La, Y, Gd, Lu or mixtures thereof, M ^π is selected from the group comprising Eu, Tb, Pr, Ce, Nd, Sm, Tm or mixtures thereof, M ^m is selected from the group comprising Hf, Zr, Ti, Ta, Nb or mixtures thereof, and M ^w is selected from the group comprising Al, Ga, Sc, Si or mixtures thereof, and O≤x≤O.1, O≤y≤O.1.

According to a preferred embodiment of the present invention, the

conversion element comprises at least one further surface which is neither an exit nor an entrance surface and where at least one, preferably all of said further surface(s) are covered with a reflective coating, preferably a mirror or a dielectric coating or a mixture thereof. By doing so, the efficiency of the conversion element(s) and the light emitting device can be enhanced further. The mirror is preferably applied by sputtering or evaporation in vacuum directly on the at least one further surface, which is neither an exit nor an entrance surface. The mirror material is preferably selected from a group comprising silver, aluminum and/or mixtures thereof. The thickness of the mirror is preferably >50nm and ≤lOOOnm A light emitting device according to the present invention may be of use in a wide variety of systems and/or applications, amongst them one or more of the following: medical lighting application systems, endoscopes - devices for photodynamic therapy

The aforementioned components, as well as the claimed components and the components to be used in accordance with the invention in the described embodiments, are not subject to any special exceptions with respect to their size, shape, material selection and technical concept such that the selection criteria known in the pertinent field can be applied without limitations.

Additional details, features, characteristics and advantages of the object of the invention are disclosed in the subclaims, figures, examples and the following description of the respective figures and examples —which in an exemplary fashion- show several preferred embodiments and examples of a light delivery device according to the invention, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a very schematic cross-sectional partial view of a light delivery device according to a first embodiment of the present invention;

Fig. 2 shows a very schematic cross-sectional partial view of a light delivery device according to a first embodiment of the present invention;

Fig. 3 shows a schematic cross-sectional partial view of the embodiment of Fig. 1 along line IV-IV in Fig. 4

Fig. 4 shows a cross-sectional view of the conversion element of the light delivery device of Figs. 1 and 3 along line H-II in Fig. 3 Fig. 5 shows a graph showing three emission spectra of a light delivery device according to a first example of the invention;

Fig.6 shows an enlarged section of the graph of Fig. 5; and Fig.7 shows a graph showing three emission spectra of a light delivery device according to a second example.

DETAILED DESCRIPTION OF EMBODIMENTS

Fig. 1 shows a very schematic cross-sectional partial view of a light delivery device 1 according to a first embodiment of the present invention. The light delivery device 1 comprises a first LED 20, a first converter substance 30, which projects light towards the conversion element 10 through a collector lens 60. From the conversion element 10, the light is then partially converted and projected towards the optical fibre 70. The optical fibre then may e.g. lead the light towards the tip of an endoscopy device (not shown in the Fig.).

In order to shift the color temperature of the LED, several auxiliary LEDs 40 are provided on a support tube 50; this part of the embodiment will be described in more detail in Fig. 3, which is an enlarged partial view of this part of the light delivery device.

As can be best seen from Fig. 1, the angle between the preferred light direction from the first LED (which in this embodiment is essentially horizontal) and the light sent out from the auxiliary LEDs (which in this embodiment is essentially vertical) is approximately 90°.

Fig.2 shows a very schematic cross-sectional partial view of a light delivery device according to a first embodiment of the present invention. This second embodiment is identical with that of Fig.1 except that a second conversion element 15 is present.

Fig. 3 shows a schematic cross-sectional partial view the embodiment of Fig. 1 along line IV-IV in Fig. 4.

Fig. 4 shows a cross-sectional view of the conversion element of the light delivery device of Figs. 1 and 3 along line H-II in Fig. 3.

As can be seen from Figs. 3 and 4, the conversion element 10 is somewhat cylindrical in shape and preferably matches the optical fibre 70. It is circumferentially surrounded by the support tube 50, which holds several sets of auxiliary LEDs 40. In this embodiment, four rows of auxiliary LEDs were used; however, it goes without saying that more (or less) auxiliary LEDs may be used, depending on the actual application. The inside surface of the support tube where no LEDs are located, is covered with a mirror. Preferably, the auxiliary LEDs are arranged closely in groups, e.g. rows, leaving large contiguous areas of the supporting tube coated with a highly reflective coating. By doing so, the total amount of LED light absorbed by the conversion element is maximized.

The conversion element 10 has two entrance surfaces Ai ₁ A ₂ (A ₂ being the "side" of the cylinder that projects towards the LED 20), resulting in an A being Ai+ A ₂ . Since there is only one exit surface with an exit surface area Ei , the numeral E, being the sum of each of the at least one exit surface areas would simply be E = Ei. The ratio of A:E is set to be >10:l and <10000:l; in this example A:E would be approximately 400: 1. However, it should be noted, that the embodiment in Fig. 3 and 4 is highly schematic and the ratio may be different for other applications.

The lighting device according to the invention is - in a merely exemplarily fashion - furthermore illustrated by the following examples together with the figures 5 to 7:

Fig.5 shows a graph showing three emission spectra of a light delivery device according to a first example of the invention, Fig.6 shows a enlarged section of the graph of Fig. 5. EXAMPLE I

In Example I, a light delivery device with the setting of Fig. 1 was used. The first LED (reference no. 20 in Fig. 1) was a InGaN LED with a peak emission at 462 nm, the first converter substance (reference no. 30 in Fig. 1) was a YAG:Ce ceramic material with the composition Y ₍ 3_ _x _ _y )Gd _x Al ₅ 0i ₂ :Cey with x=0.3 and y=0.06.

The conversion element (reference no. 10 in Fig. 1) was Y ₂ θ ₃ :Eu with a 7

% Europium doping and a density of 5.029 g/cm ³ .

The light delivery device furthermore comprises two sets of auxiliary LEDs (reference no. 40 in Fig. 1), which are also InGaN LEDs. Each set of LEDs has a power of 100% of the first LED and a peak emission at 465 nm. Figs. 5 and 6 show the spectra of the light delivery device with the first

LED only ("LED"), with one set of auxiliary LEDs switched on ("Auxl") and with both sets of auxiliary LEDs switched on ("Aux2").

The data of Fig. 5 and 6 are listed in Table I

Table I

LED Auxl Aux2

380 0.00188 0.00238 0.00288

382 0.001739 0.002239 0.002739

384 0.000654 0.001154 0.001654

386 0.000711 0.001211 0.001711

388 0.001233 0.001733 0.002233

390 0.00117 0.00167 0.00217

392 0.000811 0.001311 0.001811

394 0.000946 0.001446 0.001946

396 0.000838 0.001338 0.001838

398 0.000623 0.001123 0.001623

400 0.001035 0.001535 0.002035

402 0.001292 0.001792 0.002292

404 0.00122 0.00172 0.00222

406 0.001175 0.001675 0.002175

408 0.001278 0.001778 0.002278

410 0.001367 0.001867 0.002367

412 0.00144 0.00194 0.00244

414 0.001532 0.002032 0.002532

416 0.001929 0.002429 0.002929

418 0.002528 0.003028 0.003528

420 0.003352 0.003852 0.004352

422 0.004891 0.005391 0.005891

424 0.006672 0.007172 0.007672

426 0.008475 0.008975 0.009475

428 0.011025 0.011525 0.012025

430 0.014129 0.014629 0.015129

432 0.01841 0.01891 0.01941

434 0.023055 0.023555 0.024055

436 0.027142 0.027642 0.028142

438 0.032944 0.033444 0.033944

440 0.040675 0.041175 0.041675

442 0.047448 0.047948 0.048448

444 0.057997 0.058497 0.058997

446 0.06568 0.06618 0.06668

448 0.076898 0.077398 0.077898

450 0.088318 0.088818 0.089318

452 0.097781 0.098281 0.098781

454 0.103529 0.104029 0.104529

456 0.107177 0.107677 0.108177

458 0.109494 0.109994 0.110494

460 0.110901 0.111401 0.111901

462 0.093512 0.094012 0.094512

464 0.078426 0.078926 0.079426

466 0.065164 0.066119 0.067074

468 0.068973 0.070108 0.071243

470 0.08761 0.08811 0.08861

472 0 .096669 0 .097169 0.097669

474 0 .100671 0 .101351 0.102031

476 0 .098311 0 .098811 0.099311

478 0 .093635 0 .094135 0.094635

480 0 .088668 0 .089168 0.089668

482 0 .085616 0 .086116 0.086616

484 0 .083357 0 .083857 0.084357

486 0 .079624 0 .080124 0.080624

488 0 .073583 0 .074083 0.074583

490 0 .070694 0 .071414 0.072134

492 0 .068335 0 .068835 0.069335

494 0 .064839 0 .065339 0.065839

496 0 .063057 0 .063557 0.064057

498 0 .062375 0 .062875 0.063375

500 0 .062363 0 .062993 0.063623

502 0 .062725 0.06337 0.064015

504 0 .063773 0 .064273 0.064773

506 0 .068184 0 .070894 0.073604

508 0 .072833 0 .078278 0.083723

510 0 .076638 0 .079698 0.082758

512 0 .080117 0 .080647 0.081177

514 0 .084271 0 .085041 0.085811

516 0 .088583 0 .089083 0.089583

518 0 .092116 0 .092726 0.093336

520 0 .096028 0 .096528 0.097028

522 0 .098354 0 .098854 0.099354

524 0 .095827 0 .096327 0.096827

526 0 .094712 0 .095212 0.095712

528 0 .093644 0 .094144 0.094644

530 0 .086809 0 .087309 0.087809

532 0 .079557 0 .080057 0.080557

534 0 .078023 0 .083963 0.089903

536 0 .081832 0 .083412 0.084992

538 0 .096771 0 .099706 0.102641

540 0 .107926 0 .110741 0.113556

542 0 .116971 0 .117571 0.118171

544 0 .121157 0 .121782 0.122407

546 0 .122688 0 .123223 0.123758

548 0 .122018 0 .122573 0.123128

550 0 .121649 0 .122704 0.123759

552 0 .121918 0 .124548 0.127178

554 0 .122846 0 .125451 0.128056

556 0 .123639 0 .125474 0.127309

558 0 .123114 0 .123614 0.124114

560 0 .122137 0 .122637 0.123137

562 0 .121608 0 .122568 0.123528

564 0.120783 0.122688 0.124593

566 0 .119735 0.12131 0.122885

568 0 .118723 0 .120298 0.121873

570 0 .118546 0 .120606 0.122666

572 0 .116935 0.11762 0.118305

574 0 .115054 0 .115614 0.116174

576 0 .113432 0 .114262 0.115092

578 0 .109946 0 .111191 0.112436

580 0 .107852 0 .110017 0.112182

582 0 .113155 0.13106 0.148965

584 0 .110682 0 .124317 0.137952

586 0.10715 0.11296 0.11877

588 0 .120096 0 .159521 0.198946

590 0 .107076 0 .118441 0.129806

592 0 .106777 0 .118612 0.130447

594 0 .126511 0 .186606 0.246701

596 0 .106581 0 .124741 0.142901

598 0 .103291 0 .118781 0.134271

600 0 .112167 0 .152797 0.193427

602 0 .100955 0 .120695 0.140435

604 0 .094712 0 .104957 0.115202

606 0 .094031 0 .107736 0.121441

608 0 .094532 0 .114652 0.134772

610 0 .105648 0 .156603 0.207558

612 0.299 0.799 1.299

614 0 .175572 0 .397937 0.60.620302

616 0 .134533 0 .268638 0.402743

618 0 .088959 0 .124684 0.160409

620 0 .077779 0 .093569 0.109359

622 0 .074426 0 .088086 0.101746

624 0 .075279 0 .096684 0.118089

626 0 .074294 0 .099299 0.124304

628 0 .073762 0 .103197 0.132632

630 0 .073588 0 .107703 0.141818

632 0 .098097 0 .193427 0.288757

634 0 .060529 0 .075204 0.089879

636 0 .055331 0 .062916 0.070501

638 0 .052421 0 .058256 0.064091

640 0 .049973 0 .054533 0.059093

642 0 .047951 0 .052381 0.056811

644 0 .045942 0 .050327 0.054712

646 0 .044127 0 .048317 0.052507

648 0 .042124 0 .045564 0.049004

650 0 .040988 0 .045618 0.050248

652 0 .048088 0 .072903 0.097718

654 0 .039911 0 .050101 0.060291

656 0.03537 0 .038875 0.04238

658 0 .034343 0 .039013 0.043683

660 0.031902 0.034377 0.036852

662 0 .031165 0 .035045 0.038925

664 0 .034241 0 .048226 0.062211

666 0.02811 0 .030955 0.0338

668 0.0265 0.0287 0.0309

670 0 .025269 0 .027384 0.029499

672 0 .023972 0 .026072 0.028172

674 0.02249 0.02391 0.02533

676 0.0213 0 .022575 0.02385

678 0 .020134 0 .021254 0.022374

680 0 .019324 0 .020729 0.022134

682 0.01838 0 .019505 0.02063

684 0 .017914 0 .019504 0.021094

686 0 .017255 0.01919 0.021125

688 0 .021362 0 .034522 0.047682

690 0 .017832 0 .024502 0.031172

692 0 .014795 0.01648 0.018165

694 0 .017148 0 .026443 0.035738

696 0 .013255 0 .015435 0.017615

698 0.0121 0.01304 0.01398

700 0 .011542 0 .012727 0.013912

702 0 .011226 0 .012981 0.014736

704 0 .011728 0 .015483 0.019238

706 0 .013805 0 .023045 0.032285

708 0 .026806 0 .066926 0.107046

710 0 .029198 0 .076303 0.123408

712 0 .013137 0 .024182 0.035227

714 0 .018797 0 .043992 0.069187

716 0 .008111 0 .009701 0.011291

718 0.00744 0 .008405 0.00937

720 0 .006897 0 .007732 0.008567

722 0 .006787 0 .007587 0.008387

724 0 .006289 0 .006994 0.007699

726 0 .005959 0 .006624 0.007289

728 0 .005447 0 .006077 0.006707

730 0 .005466 0 .006141 0.006816

732 0 .005346 0 .005961 0.006576

734 0 .004935 0 .005435 0.005935

736 0 .004677 0 .005177 0.005677

738 0 .004646 0 .005146 0.005646

740 0 .004793 0 .005293 0.005793

742 0 .004545 0.0056 0.006655

744 0 .004599 0 .006199 0.007799

746 0 .003901 0 .004401 0.004901

748 0 .003995 0.00496 0.005925

750 0 .003715 0 .004215 0.004715

752 0 .003625 0 .004125 0.004625

754 0 .003318 0 .003818 0.004318

756 0.003133 0.003633 0.004133

758 0 .003193 0 .003693 0.004193

760 0.00308 0.00358 0.00408

762 0 .003095 0 .003595 0.004095

764 0 .002751 0 .003251 0.003751

766 0 .002666 0 .003166 0.003666

768 0 .002573 0 .003073 0.003573

770 0 .002335 0 .002835 0.003335

772 0 .002312 0 .002812 0.003312

774 0 .001938 0 .002438 0.002938

776 0 .001862 0 .002362 0.002862

778 0 .001972 0 .002472 0.002972

780 0 .001951 0 .002451 0.002951

Further data ofExample I are given in Table II:

Table II

It can be clearly seen that a shift of the color temperature over approx. 1600K is possible without any deterioration of the lighting properties, such as the color rendering index Ra of the light delivery device.

Fig.7 shows a graph with three emission spectra of a light delivery device according to a second example of the invention.

EXAMPLE II

In Example II, a light delivery device with the setting of Fig. 1 was used.

The first LED (reference no. 20 in Fig. 1) was an InGaN LED with a peak emission at 462 nm, the first converter substance (reference no. 30 in Fig. 1) was a YAG:Ce ceramic material with the composition Y ₍ 3_ _x _ _y )Gd _x Al ₅ 0i2:Cey with x=0.3 and y=0.06.

The conversion element on Example II is CaS :Eu with 0.1 % Europium. The light delivery device furthermore comprises two sets of auxiliary

LEDs (reference no. 40 in Fig. 1) , which are also InGaN LEDs emitting at 450 nm. Each set of LEDs has a "strength" of 50% of the first LED.

Fig. 7 shows the spectra of the light delivery device with the first LED only ("LED"), with one set of auxiliary LEDs switched on ("Auxl") and with both sets of auxiliary LEDs swithched on ("Aux2").

The data of Fig. 7 are listed in Table III: Table III

LED Aux 1 Aux 2

380 0.002731 0.002811 0.002891

382 0.00246 0.00254 0.00262

384 0.002295 0.002375 0.002455

386 0.002183 0.002263 0.002343

388 0.0021 0.00218 0.00226

390 0.002063 0.002143 0.002223

392 0.001984 0.002064 0.002144

394 0.001932 0.002012 0.002092

396 0.001891 0.001971 0.002051

398 0.001885 0.001965 0.002045

400 0.001894 0.001974 0.002054

402 0.001904 0.001984 0.002064

404 0.001916 0.001996 0.002076

406 0.00201 0.00209 0.00217

408 0.002198 0.002278 0.002358

410 0.002487 0.002567 0.002647

412 0.00291 0.00299 0.00307

414 0.003532 0.003612 0.003692

416 0.004441 0.004521 0.004601

418 0.005643 0.005723 0.005803

420 0.007188 0.007268 0.007348

422 0.009126 0.009206 0.009286

424 0.011543 0.011623 0.011703

426 0.014461 0.014541 0.014621

428 0.017876 0.017956 0.018036

430 0.021857 0.021937 0.022017

432 0.026492 0.026572 0.026652

434 0.031853 0.031933 0.032013

436 0.037928 0.038008 0.038088

438 0.044757 0.044837 0.044917

440 0 .052341 0 .052421 0 .052501

442 0.06054 0.06062 0.0607

444 0 .069068 0 .069148 0 .069228

446 0.0776 0.07768 0.07776

448 0 .085827 0 .085907 0 .085987

450 0 .093335 0 .093415 0 .093495

452 0 .099715 0 .099795 0 .099875

454 0 .104735 0 .104815 0 .104895

456 0 .108405 0 .108485 0 .108565

458 0 .110776 0 .110856 0 .110936

460 0 .111859 0 .111939 0 .112019

462 0 .111729 0 .111809 0 .111889

464 0 .110624 0 .110704 0 .110784

466 0.10875 0.10883 0.10891

468 0 .106153 0 .106233 0 .106313

470 0 .102863 0 .102943 0 .103023

472 0 .099002 0 .099082 0 .099162

474 0 .094808 0 .094888 0 .094968

476 0 .090407 0 .090487 0 .090567

478 0 .085859 0 .085939 0 .086019

480 0 .081277 0 .081357 0 .081437

482 0 .076808 0 .076888 0 .076968

484 0 .072592 0 .072672 0 .072752

486 0 .068674 0 .068754 0 .068834

488 0.06512 0.0652 0.06528

490 0 .062011 0 .062091 0 .062171

492 0 .059401 0 .059481 0 .059561

494 0 .057342 0 .057422 0 .057502

496 0 .055892 0 .055972 0 .056052

498 0 .055102 0 .055182 0 .055262

500 0 .054976 0 .055056 0 .055136

502 0 .055448 0 .055528 0 .055608

504 0 .056473 0 .056553 0 .056633

506 0 .057981 0 .058061 0 .058141

508 0 .059874 0 .059954 0 .060034

510 0.06208 0.06216 0.06224

512 0 .064504 0 .064584 0 .064664

514 0 .067104 0 .067184 0 .067264

516 0 .069813 0 .069893 0 .069973

518 0 .072572 0 .072652 0 .072732

520 0 .075336 0 .075416 0 .075496

522 0 .078019 0 .078099 0 .078179

524 0.08058 0.08066 0.08074

526 0 .082985 0 .083065 0 .083145

528 0 .085209 0 .085289 0 .085369

530 0 .087237 0 .087317 0 .087397

532 0 .089072 0 .089152 0 .089232

534 0.090731 0.090811 0.090891

536 0 .092226 0 .092306 0 .092386

538 0 .093548 0 .093628 0 .093708

540 0 .094726 0 .094806 0 .094886

542 0.09578 0.09586 0.09594

544 0.0967 0.09678 0.09686

546 0 .097504 0 .097584 0 .097664

548 0 .098204 0 .098284 0 .098364

550 0 .098803 0 .098883 0 .098963

552 0 .099295 0 .099375 0 .099455

554 0 .099666 0 .099746 0 .099826

556 0 .099941 0 .100021 0 .100101

558 0.10014 0 .100253 0 .100366

560 0 .100248 0 .100352 0 .100457

562 0 .100278 0 .100419 0.10056

564 0 .100233 0.10041 0 .100586

566 0.10013 0 .100255 0.10038

568 0 .099938 0 .100226 0 .100514

570 0 .099644 0 .099935 0 .100225

572 0 .099263 0 .099655 0 .100047

574 0.09881 0 .099252 0 .099693

576 0 .098291 0 .098948 0 .099605

578 0 .097708 0.09838 0 .099052

580 0 .097084 0 .098111 0 .099137

582 0 .096427 0 .097766 0 .099105

584 0 .095733 0 .097249 0 .098765

586 0 .094989 0 .096655 0 .098321

588 0 .094207 0 .096499 0 .098791

590 0 .093417 0 .096078 0 .098739

592 0 .092576 0 .096145 0 .099715

594 0 .091684 0 .095957 0 .100231

596 0 .090785 0 .095981 0 .101177

598 0 .089914 0.09634 0 .102765

600 0 .089023 0 .097329 0 .105635

602 0 .088138 0 .097263 0 .106389

604 0 .087334 0 .097683 0 .108031

606 0 .086558 0 .099057 0 .111555

608 0.08584 0 .101103 0 .116365

610 0 .085138 0 .102026 0 .118914

612 0 .084485 0 .104488 0.12449

614 0 .083873 0 .107333 0 .130793

616 0.08323 0 .109446 0 .135663

618 0 .082661 0 .113232 0 .143802

620 0 .082144 0 .116123 0 .150101

622 0 .081627 0 .118431 0 .155235

624 0.08123 0 .122007 0 .162784

626 0 .080804 0 .124579 0 .168354

628 0.08048 0 .128565 0 .176649

630 0.080106 0.132753 0.1854

632 0 .079787 0 .135032 0 .190277

634 0 .079415 0 .140028 0 .200642

636 0 .078916 0 .141712 0 .204508

638 0 .078449 0 .145427 0 .212405

640 0 .077836 0 .146472 0 .215107

642 0 .077139 0 .150875 0 .224611

644 0 .076284 0 .150698 0 .225112

646 0 .075289 0 .150925 0 .226561

648 0 .074195 0 .152055 0 .229916

650 0 .072828 0 .150963 0 .229098

652 0 .071378 0 .149344 0 .227309

654 0 .069852 0 .149852 0 .229852

656 0 .068139 0 .145939 0 .223738

658 0 .066397 0 .143834 0 .221272

660 0 .064552 0 .138972 0 .213393

662 0 .062615 0 .136383 0 .210151

664 0 .060556 0 .133304 0 .206053

666 0.0584 0 .129308 0 .200216

668 0 .056123 0 .125063 0 .194003

670 0 .053743 0 .120684 0 .187625

672 0.05133 0 .113789 0 .176248

674 0 .049083 0 .108819 0 .168556

676 0 .046732 0 .103957 0 .161182

678 0 .044451 0 .097638 0 .150824

680 0 .042273 0 .091529 0 .140785

682 0 .040124 0 .086984 0 .133844

684 0 .038025 0 .083943 0 .129862

686 0 .035843 0 .076383 0 .116923

688 0 .033855 0 .073202 0 .112548

690 0 .031863 0 .068753 0 .105643

692 0 .029922 0 .062992 0 .096063

694 0 .028121 0 .059684 0 .091248

696 0 .026411 0 .055107 0 .083803

698 0 .024817 0.0518 0 .078783

700 0 .023267 0.04813 0 .072993

702 0 .021803 0 .044705 0 .067606

704 0 .020463 0 .041375 0 .062287

706 0 .019186 0 .038765 0 .058343

708 0 .017968 0 .035719 0.05347

710 0 .016772 0 .033093 0 .049414

712 0 .015685 0 .030275 0 .044866

714 0 .014667 0 .029027 0 .043387

716 0 .013678 0 .026584 0 .039491

718 0 .012728 0.02487 0 .037012

720 0 .011838 0 .021897 0 .031956

722 0 .011087 0 .020362 0 .029638

724 0 .010336 0 .018908 0.02748

726 0.009658 0.017608 0.025558

728 0.00902 0.015997 0. 022974

730 0.008502 0.014717 0. 020931

732 0.007991 0.013938 0. 019885

734 0.007478 0.012436 0. 017395

736 0.007028 0.012045 0. 017063

738 0.00659 0.010689 0. 014789

740 0.006218 0.010233 0. 014248

742 0.005813 0.009442 0. 013072

744 0.005459 0.008447 0. 011434

746 0.005142 0.007815 0. 010488

748 0.004859 0.007119 0. 009379

750 0.004616 0.007121 0. 009627

752 0.004355 0.006159 0. 007964

754 0.004116 0.006123 0. 008129

756 0.003899 0.005788 0. 007677

758 0.003704 0.005228 0. 006752

760 0.003509 0.00523 0. 006952

762 0.00331 0.004353 0. 005396

764 0.003101 0.004161 0. 005221

766 0.002911 0.003969 0. 005027

768 0.002731 0.003769 0. 004806

770 0.002567 0.003607 0. 004647

772 0.002475 0.003363 0. 004251

774 0.002384 0.003092 0.0038

776 0.002342 0.002933 0. 003525

778 0.002329 0.002724 0. 003118

780 0.002339 0.002902 0. 003465

Further data ofExample II are given in Table IV

Table IV

It can be clearly seen that a shift of the color temperature over approx. 1700K is possible without any deterioration in the lighting properties, such as the Ra of the light delivery device.

In both examples it is possible to simply "add" red light, i.e. the spectra in the wavelength range of 380 to 580 nm are more or less identical for "LED", "Auxl" as well as "Aux2".

It should be noted that in both examples the light flux even increases by switching on the LED groups Auxl and Aux 2. If a constant flux is required, the first LED may be dimmed when the Auxl and Aux2 LEDs are switched on. In this case the color temperature will be decreased even further with the full power of the Auxl and Aux2 LEDs added. It is evident that the light flux of all LEDs can be tuned to any desired value between the maximum power applicable to the LED package and zero. Power can be modified either by increasing and decreasing the DC voltage and current or by application of fast current and voltage pulses at a frequency > 10 Hz and modifying the ratio of the on and off-time of the power.

The particular combinations of elements and features in the above detailed embodiments are exemplary only; the interchanging and substitution of these teachings with other teachings in this patent application and the patents/applications incorporated by reference are also expressly contemplated. As those skilled in the art will recognize, variations, modifications, and other implementations of what is described herein can occur to those of ordinary skill in the art without departing from the spirit and the scope of the invention as claimed. Accordingly, the above description is by way of example only, and is not intended to be limiting. The invention's scope is defined in the following claims and the equivalents thereto. Furthermore, reference signs used in the description and claims do not limit the scope of the invention as claimed.