Light source with disinfection function

Abstract

The invention provides a light generating system (1000) configured to generate system light (1001), wherein the light generating system (1000) comprises a first light generating device (110), wherein: (A) the first light generating device (110) comprises a first light source (10) and a first luminescent converter (210); (B) the first light source (10) comprises a solid state light source, wherein the first light source (10) is configured to generate first light source light (11) having a first light source centroid wavelength (.sub.s,1) selected from the range of 380-420 inn; (C) the first luminescent converter (210) is configured to convert at least part of the first light source light (11) into first converter light (211) having a first converter centroid wavelength (.sub.c, 1) selected from the green-yellow wavelength range; (D) the first light generating device (110) is configured to generate first device light (111) having a spectral power distribution in the wavelength range of 380-780 nm with at least 60% of the spectral power provided by the first light source light (11) and at maximum 40% of the spectral power provided by the first converter light (211).

Claims

1. A light generating system configured to generate system light, wherein the light generating system comprises a first light generating device; wherein: the first light generating device comprises a first light source and a first luminescent converter; the first light source comprises a solid state light source, wherein the first light source is configured to generate first light source light having a first light source centroid wavelength selected from the range of 380-420 nm; the first luminescent converter is configured to convert part of the first light source light into first converter light having a first converter centroid wavelength selected from the green-yellow wavelength range; the first light generating device is configured to generate first device light having a spectral power distribution in the wavelength range of 380-780 nm with at least 60% of the spectral power provided by the first light source light and at maximum 40% of the spectral power provided by the first converter light; wherein the first luminescent converter comprises a first matrix material and a first luminescent material, wherein the first luminescent material has a first weight percentage CW1 relative to the total weight of the first luminescent converter; wherein the light generating system further comprises a second light generating device, wherein the second light generating device comprises a second light source and a second luminescent converter; wherein the second light source comprises a solid state light source, wherein the second light source is configured to generate second light source light; wherein the second luminescent converter is configured to convert at least part of the second light source light into second converter light; and wherein the second light generating device is configured to generate second device light having a spectral power distribution in the wavelength range of 380-780 nm with at least 60% of the spectral power provided by the second converter light and at maximum 40% of the spectral power provided by the second light source light; wherein the second luminescent converter comprises a second matrix material and a second luminescent material, wherein the second luminescent material has a second weight percentage CW2 relative to the total weight of the second luminescent converter; and wherein CW1/CW20.5.

2. The light generating system according to claim 1, wherein the first light source centroid wavelength is selected from the range of 395-415 nm, wherein the first luminescent converter is configured to convert the first light source light into first converter light having the first converter centroid wavelength selected from the green wavelength range.

3. The light generating system according to claim 1, wherein CW110 wt %; wherein the first light source centroid wavelength is selected from the range of 400-410 nm; and wherein the first device light has a color point with u selected from the range of 0.10-0.22 and with v selected from the range of 0.30-0.55.

4. The light generating system according to claim 1, wherein the second device light is white light.

5. The light generating system according to claim 4, wherein the second light source light having a second light source centroid wavelength selected from the range of 445-480 nm; wherein the second device light has a correlated color temperature selected from the range of 1800-6500 K, and a color point within 0-15 SDCM from the black body locus, and a color rendering index of at minimum 70.

6. The light generating system according to claim 1, wherein CW1/CW20.3; wherein the first luminescent material comprises particulate material, and wherein the first matrix material comprises a resin; wherein the second luminescent material comprises particulate material, and wherein the second matrix material comprises a resin.

7. The light generating system according to claim 1, wherein CW2 is at least 20 wt %.

8. The light generating system according to claim 1, wherein: at least 50 wt % of the first luminescent material has a particle dimension selected from the range of 1-20 m; relative to a spectral power distribution of the first converter light in the range of 380-780 nm, at maximum 20% of the spectral power is within the range of 585-780 nm; and relative to a spectral power distribution of the second device light in the range of 380-780 nm, at maximum 30% of the spectral power is provided by the second light source light.

9. The light generating system according to claim 1, wherein the first luminescent material comprises one or more of a Eu.sup.2+based luminescent material and a Ce.sup.3+based luminescent material.

10. The light generating system according to claim 1, wherein the system light has a correlated color temperature selected from the range of 1800-6500 K, and a color point within 0-10 SDCM from the black body locus, and a color rendering index of at minimum 70.

11. The light generating system according to claim 1, further comprising a control system, wherein the control system is configured to control the system light in dependence of one or more of an input signal of a user interface, a sensor signal, and a timer.

12. The light generating system according to claim 11, wherein the control system is configured to control the first light generating device and the second light generating device individually.

13. The light generating system according to claim 1, further comprising a support, wherein: the light generating system comprises a plurality n1 of first light generating devices and a plurality n2 of second light generating devices configured supported by a support; the plurality n1 of first light generating devices and the plurality n2 of second light generating devices comprise a subset comprising at least two first light generating devices and more than two second light generating devices, wherein all second light generating devices in the subset have equal second pitches.

14. A lighting device selected from the group of a lamp, a luminaire, a disinfection device, and an optical wireless communication device, comprising the light generating system according to claim 1.

15. A method for treating at least part of a space or of an object, wherein the method comprises providing system radiation comprising the first device light in the space or to the object, using the light generating system as defined in claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

(2) FIGS. 1a-1e schematically depict some aspects and embodiments;

(3) FIG. 2 shows some emission and excitation spectra;

(4) FIG. 3 shows a uv diagram with some light generating device (light) color points;

(5) FIGS. 4a-4b show some LED spectra in dependence of the presence of a (first) luminescent material;

(6) FIG. 5 shows an embodiment of system light; and

(7) FIG. 6 schematically depicts some application embodiments.

(8) The schematic drawings are not necessarily to scale.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(9) FIGS. 1a-1b schematically depict some embodiments and aspects. FIGS. 1a, embodiments I and II, and FIG. 1b, embodiments II, schematically depicts embodiments of a light generating system 1000 configured to generate system light 1001. The light generating system 1000 especially comprises a first light generating device 110. The first light generating device 110 may comprise a first light source 10 and a first luminescent converter 210. Especially, the first light source 10 may comprise a solid state light source. The first light source 10 may be configured to generate first light source light 11 having a first light source centroid wavelength .sub.s,1, e.g. selected from the range of 380-430 nm, such as 380-425 nm, more especially 380-420 nm. The first luminescent converter 210 may be configured to convert (at least) part of the first light source light 11 into first converter light 211 having a first converter centroid wavelength .sub.c,1, e.g. selected from the green-yellow wavelength range. Further, the first light generating device 110 may be configured to generate first device light 111 having a spectral power distribution in the wavelength range of 380-780 nm with e.g. at least 60% of the spectral power provided by the first light source light 11 and at maximum 40% of the spectral power provided by the first converter light 211.

(10) In embodiments, the first light source centroid wavelength .sub.s,1 may be selected from the range of 395-415 nm.

(11) In embodiments, the first luminescent converter 210 may comprise a first matrix material 215 and a first luminescent material 216, wherein the first luminescent material 216 has a first weight percentage CW1 relative to the total weight of the first luminescent converter 210. In embodiments, CW110 wt %.

(12) Especially, the first luminescent converter 210 may be configured to convert the first light source light 11 into first converter light 211 having the first converter centroid wavelength .sub.c,1 selected from the green wavelength range. However, other options may also be possible.

(13) In embodiments, the first device light 111 may have a correlated color temperature selected from the range of 6000-25000 K. Further, the first device light 111 may have a (first device light) color point selected within 0-20 SDCM from the black body locus. Yet further, the first device light 111 may have and a color rendering index of at maximum 70. In embodiments, the first light source centroid wavelength .sub.s,1 is selected from the range of 400-410 nm.

(14) For an energy efficient and cost-efficient solution, a high efficiency is requested for both the first light generating device and second light generating device (like a white LED package). A device comprising a light source of blue+white LEDs may results in an overall efficacy reduction of around 22% below the standard white LED based device. This may be undesirable.

(15) Some devices may have a relatively low probability of outcoupling from the clear silicone layer on top of the chip, e.g. as the surface is usually concave, at best nearly flat. An example of a first light generating device 110, but yet without first luminescent material, but with resin, here indicated with reference 215, is schematically depicted in FIG. 1b, embodiment I, on the left. An emission spectrum thereof is shown on the right of embodiment I. Essentially, the first device light of such device without first luminescent material, may consist of the first light source light 11.

(16) Adding a violet light generating device may also shift the color point towards the blue (lower v). In combination with standard white light generating devices this may limit the amount of violet light that can be added. A too high contribution of violet may shift the color point out of the ANSI-bin.

(17) Amongst others, the invention proposes to add a minimum volume of phosphor particles in a short wavelength, especially about 405 nm, LED package, to provide a first light generating device, to promote light outcoupling and so improve efficiency, and induce some phosphor conversion to achieve a favorable color point. Especially, the combination of the violet pump light and the phosphor converted light can have a color point close to the BBL, allowing the addition of higher amounts of violet light in combination with standard white light generating devices, such as LEDs.

(18) Using a violet light generating devices (without scatterer or phosphor) may result in a lower package efficiency as some of light is trapped inside the clear silicone (protection) layer on top of the chip. A portion of the light emitted by the chip will undergo total internal reflection at the air-silicone interface and will eventually get absorbed inside the package (by e.g. the die). Adding phosphor particles in the clear silicone may increase the light outcoupling due to more scattering inside the clear silicone layer, resulting in a larger probability of outcoupling.

(19) FIG. 1b schematically shows the principle. The slightly changed spectrum is for this application beneficial (whitish color point). In a combination with standard white light generating devices, this may result in a white (within ANSI) color point. In a pure disinfection mode (switching on the 405 nm LED only), the emission will be cool white with a low color rendering. This mode may e.g. only used when no people are present in the room, therefore the low color rendering properties are acceptable (applying this concept with standard blue, green or red light generating devices would not be acceptable as it impacts the purity of the direct colors).

(20) Hence, amongst others a bit of green/yellow phosphor may be provided in the 405 nm chip package, to provide a first light generating device, such that the color point of this package, i.e. the resulting first device light, shifts towards the BBL. At the same time, the extraction efficiency may thereby increase.

(21) Referring to FIGS. 1c-1e, in specific embodiments the light generating system 1000 may further comprising a second light generating device 120. The second light generating device 120 may comprise a second light source 20 and a second luminescent converter 220. The second light source 20 may comprise a solid state light source. The second light source 20 may be configured to generate second light source light 21 (such as having a second light source centroid wavelength (.sub.s,2) selected from the range of 440-490 nm). The second luminescent converter 220 may be configured to convert at least part of the second light source light 21 into second converter light 221 (such as having a second converter centroid wavelength (.sub.c,2) selected from the green-red wavelength range). The second light generating device 120 may be configured to generate second device light 121 having a spectral power distribution in the wavelength range of 380-780 nm with at least 60% of the spectral power provided by the second converter light 221 and at maximum 40% of the spectral power provided by the second light source light 21. The second device light 121 may be white light. A first device light spectral power distribution of the first device light 111 and a second device light spectral power distribution of the second device light 121 may differ (see also below).

(22) In embodiments, the second light source centroid wavelength (.sub.s,2) may be selected from the range of 445-480 nm. The second luminescent converter 220 may comprise a second matrix material 225 and a second luminescent material 226. The second luminescent material 226 may have a second weight percentage CW2 relative to the total weight of the second luminescent converter 210. In embodiments, CW2 may be at least 20 wt %.

(23) The second device light 121 may have a correlated color temperature selected from the range of 1800-6500 K, and a (second device light) color point within 0-15 SDCM from the black body locus, and a color rendering index of at minimum 70.

(24) The first luminescent material 216 may comprise particulate material. The first matrix material 215 may comprise a resin (especially a silicone resin). The second luminescent material 226 may comprise particulate material. The second matrix material 225 may comprise a resin (especially a silicone resin). In embodiments, the first luminescent material 216 may comprise one or more of a Eu.sup.2+-based luminescent material and a Ce.sup.3+-based luminescent material.

(25) In embodiments, CW1/CW20.3. In embodiments, the first luminescent material 216 may have a first volume percentage CV1 of first luminescent material 216 in the first luminescent converter 210. Further, the second luminescent material 226 may have a second volume percentage V2 of the second luminescent material 226 in the second luminescent converter 220. In embodiments, CV1/V20.3.

(26) In embodiments, at least 50 wt % of the first luminescent material 216 has a particle dimension selected from the range of 1-20 m.

(27) In embodiments, relative to a spectral power distribution of the first converter light 211 in the range of 380-780 nm, at maximum 20% of the spectral power may be within the range of 585-780 nm.

(28) In embodiments, relative to a spectral power distribution of the second device light 121 in the range of 380-780 nm, at maximum 30% of the spectral power may be provided by the second light source light 21.

(29) In specific embodiments, the system light 1001 may have a correlated color temperature selected from the range of 1800-6500 K, and a (system light) color point within 0-10 SDCM from the black body locus, and a color rendering index of at minimum 70.

(30) In embodiments, the light generating system 1000 may further comprising a control system 300. Especially, the control system 300 may be configured to control the system light 1001 in dependence of one or more of an input signal of a user interface, a sensor signal (of a sensor), and a timer. In embodiments, the control system 300 may be configured to control the first light generating device 110 and the second light generating device 120 individually.

(31) Referring to FIG. 1e, the light generating system 1000 may further comprise a support 600. The light generating system 1000 may comprise a plurality n1 of first light generating devices 110 and a plurality n2 of second light generating devices 120 (both) configured supported by a support 600. In embodiments, the first light generating devices 110 are configured in one or more rows. In embodiments, the plurality n1 of first light generating devices 110 and the plurality n2 of second light generating devices 120 may comprise a subset 1050 comprising at least two first light generating devices 110 and more than two second light generating devices 120. In specific embodiments, all second light generating devices 120 in the subset 1050 have equal second pitches p2. Reference P1 refers to the pitch of the first light generating devices 110.

(32) In embodiments, options range from adding the LEDs in the same row (I, II) or adding them next to the row of white LEDs (III). Also, in option I and III the resulting white LED positioning may be kept identical to the original white LED L2. As a result, the white light uniformity may be substantially unchanged; there may be no spottiness due to the violet as will be the case in option II. Proper luminaire optical design may still result in acceptable luminaire solutions with option II.

(33) FIG. 2 shows a short wavelength blue emission peak at about 405 nm peak wavelength/first light source centroid wavelength .sub.s,1, as well as excitation spectra, indicated with the starting letter X and emission spectra indicated with the starting letter M of different luminescent materials. The luminescent materials are indicated with the second letters a, b, c, and d, and are: a divalent europium based narrow green phosphor (a), a divalent europium based silicate (b), a gallium comprising YAG-type luminescent material (c), and a lutetium comprising YAG-type material (d).

(34) The excitation spectra (Xa and Xb) of the divalent europium based narrow green phosphor (a) and the divalent europium based silicate (b), respectively, have a good overlap with the first light source light 11; the excitation spectra (Xc and Xd) of the gallium comprising YAG-type luminescent material (c), and the lutetium comprising YAG-type material (d), respectively, have an overlap which is higher at the long wavelength side than at the short wavelength side of the first light source light 11.

(35) By way of example centroid wavelengths .sub.c,1 are schematically indicated for the emission ma of a divalent europium based narrow green phosphor (a), and for the emission mb of the divalent europium based silicate (b). Note that the schematically indicated centroid wavelengths herein may not necessarily exactly match with the calculated centroid wavelengths, as these centroid wavelengths are herein only indicated for reference purposes. Further, note that the centroid wavelengths do not necessarily coincide with peak wavelengths or maxima of emission bands.

(36) FIG. 3 depicts a uv color point plot of different light generating devices. By way of example, different standard white LEDs (2700 K, 3000 K, 4000 K and 6500 K) were combined with a violet LED. The white LEDs may e.g. have a high CRI, such as in embodiments CRI of 90. The violet LED may e.g. contain some divalent europium based phosphor, here especially in embodiments BaSrSiO.sub.4:Eu.sup.2+. The larger the amount of luminescent material, the higher the v value.

(37) Note that the color point of the first device light may thus be on a line connecting the color point of the second device light and color point of the desired application color point (and thus all three color points may be on the same line). The color point of first device light can be relatively far from BBL when the CCT of the second device light is relatively low. The color point of first device light can be relatively close to the BBL when the CCT of the second device light is relatively high. This is schematically shown using the 6500 K second device light example. A dashed dotted line b from a color point on or close to the BBL to a system light color point also on or close to the BBL would follow this dashed dotted line. The intersection with the line a, which shows the color point of the first device light as function of the relative amount (or volume) of first luminescent material (in a matrix), provides the color point of the first device light. Line c indicates part of the boundary of the color triangle.

(38) The light of standard white LEDs is mixed with the light from violet pumped divalent europium based phosphor LEDs in different fractions, to generate color points at higher CCTs. Depending on the color point of the divalent europium based phosphor/405 nm LED the color point can go below BBL (too low divalent europium based phosphor thickness), along the BBL, or above BBL (too high divalent europium based phosphor thickness).

(39) For the 2700 K white LED, the required phosphor thickness can be determined to generate color points along the BBL. The CCT of the violet LED is 13000 K, with a CRI of 39 and an R9 of 218. In the (combined color) point with the highest CCT (3500 K) approximately 19% of the lumen flux is generated by the violet/BaSrSiO.sub.4:Eu.sup.2+ LED; CRI of the combined white spectrum is still 91. The white spectrum contains 1.7 mW of violet light/Lm.

(40) For the 4000K white LED, the required phosphor thickness can be determined to generate color points along the BBL. The CCT of the violet LED would be 21600 K, with a CRI of 39 and an R9 of 198. In the (combined color) point with the highest CCT (5000K) approximately 16% of the lumen flux is generated by the violet/divalent europium based phosphor LED; CRI of the white spectrum is still 89. The white spectrum may contain 1.9 mW of violet light/Lm.

(41) As can be derived from FIG. 3, in specific embodiments the first device light 111 may have a color point with u selected from the range of 0.10-0.22 and with v selected from the range of 0.30-0.55.

(42) Cerium based green phosphors, such as in particular LuAG:Ce, may have a desirable excitation spectrum, see FIG. 4a. FIG. 4a shows in embodiment I the spectrum of the violet-based light generating device (first device light 111) as function of the amount of first luminescent material and in embodiment II the (remaining) emission of the first light source light 11 as function of the amount of first luminescent material. In FIG. 4b this is shown for a divalent europium based luminescent material. LuAG:Ce (FIG. 4a) absorbs mainly the long-wavelength part of the first light source light, which is expected to be slightly less effective in inactivating pathogens. So the more effective part of the spectrum remains.

(43) The loss of 405 nm light by conversion can be compensated by increasing the relative amount of violet-based light generating devices, and the efficiency loss due to the larger Stokes shift for the phosphor converted light is very limited (1%). The increase in PE due to the better outcoupling is more than expected to compensate for this effect.

(44) FIG. 5 schematically depicts an embodiment of system light 1001, based on the composition with first device light 111 and second device light 121. Referring to the second device light 121, the spectral power distribution of the second device light 121 (in the wavelength range of 380-780 nm) may comprise in the range of 10-30% of the spectral power provided by the second light source light 21 and in the range of 70-90% of the spectral power provided by the second converter light.

(45) FIG. 6 schematically depicts an embodiment of a luminaire 2 comprising the light generating system 1000 as described above. Reference 301 indicates a user interface which may be functionally coupled with the control system 300 comprised by or functionally coupled to the light generating system 1000. FIG. 6 also schematically depicts an embodiment of lamp 1 comprising the light generating system 1000. Reference 3 indicates a projector device or projector system, which may be used to project images, such as at a wall, which may also comprise the light generating system 1000. Hence, FIG. 6 schematically depicts embodiments of a lighting device 1200 selected from the group of a lamp 1, a luminaire 2, a projector device 3, a disinfection device, a photochemical reactor, and an optical wireless communication device, comprising the light generating system 1000 as described herein. In embodiments, such lighting device may be a lamp 1, a luminaire 2, a projector device 3, a disinfection device, or an optical wireless communication device. Lighting device light escaping from the lighting device 1200 is indicated with reference 1201. Lighting device light 1201 may essentially consist of system light 1001, and may in specific embodiments thus be system light 1001.

(46) Amongst others, with the present invention a method for treating at least part of a space 1300 or of an object (external of the light generating system 1000 or the light generating device 1200) may be provided. The method may comprise providing system radiation 1001 comprising the first device light 111 in the space 1300 or to the object, using the light generating system 1000 as described herein or the lighting device 1200 as described herein.

(47) The term plurality refers to two or more.

(48) The terms substantially or essentially herein, and similar terms, will be understood by the person skilled in the art. The terms substantially or essentially may also include embodiments with entirely, completely, all, etc. Hence, in embodiments the adjective substantially or essentially may also be removed. Where applicable, the term substantially or the term essentially may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%.

(49) The term comprise also includes embodiments wherein the term comprises means consists of.

(50) The term and/of especially relates to one or more of the items mentioned before and after and/or. For instance, a phrase item 1 and/or item 2 and similar phrases may relate to one or more of item 1 and item 2. The term comprising may in an embodiment refer to consisting of but may in another embodiment also refer to containing at least the defined species and optionally one or more other species.

(51) Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

(52) The devices, apparatus, or systems may herein amongst others be described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation, or devices, apparatus, or systems in operation.

(53) It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims.

(54) In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

(55) Use of the verb to comprise and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Unless the context clearly requires otherwise, throughout the description and the claims, the words comprise, comprising, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of including, but not limited to.

(56) The article a or an preceding an element does not exclude the presence of a plurality of such elements.

(57) The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim, or an apparatus claim, or a system claim, enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. In yet a further aspect, the invention (thus) provides a software product, which, when running on a computer is capable of bringing about (one or more embodiments of) the method as described herein.

(58) The invention also provides a control system that may control the device, apparatus, or system, or that may execute the herein described method or process. Yet further, the invention also provides a computer program product, when running on a computer which is functionally coupled to or comprised by the device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system.

(59) The invention further applies to a device, apparatus, or system comprising one or more of the characterizing features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and/or shown in the attached drawings.

(60) The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.