FIELD OF THE INVENTION

The invention relates to a light-based disinfection device comprising a parabolic reflector, preferably a single curved parabolic reflector, and at least one LED package comprising an ultraviolet LED and pre-collimator optic. The invention may further relate to the assembly of a parabolic reflector and said at least one LED package.

BACKGROUND OF THE INVENTION

Societal health is periodically contested by virus outbreaks, such as seasonal symptomatic influenza A/B outbreak, SARS, MERS, COVID-19. Future outbreaks, mutations, epidemics, and pandemics are not excluded. These developments have clearly risen the demand for light-based disinfection devices to disinfect air from pathogens, such as for example ultraviolet (UV) light-based disinfection devices.

Ultraviolet light-based disinfection devices may typically employ light with wavelengths in the ultraviolet-C range (UV-C), namely due to the strong germicidal effect of UV-C light. However, various spectra of ultraviolet light may also be hazardous to humans, in certain doses and time of exposures.

Therefore, upper-air ultraviolet light-based disinfection devices, which generate a sheet-like beam of UVC radiation along a ceiling of a space, are required to ensure that said sheet-like beam remains within a narrow spread of about 5 degrees parallel to the ceiling, so as to prevent stray light into the space.

For upper-air ultraviolet light-based disinfection devices with Ultraviolet (UV) Light Emitting Diodes (LED), said sheet-like beam is advantageously achieved by placing an array of such UV-LEDs in the focal point or focal line of an extruded parabolic reflector.

However, considering such an extruded parabolic reflector, research of Signify has observed that some rays may not be captured by the reflector, and may travel upward, toward the ceiling of the space. This may result in a small portion of ultraviolet (UV) stray light, which might turn out to be harmful in case these rays are reflected from the ceiling into the space. How much stray light escapes depends on the type of UV LED, as there are different package architectures giving different radiation profiles. Hence, there is clear need for a solution preventing stray light, which is robust for the use of different types of UV LED.

Furthermore, considering the manufacturing of such an extruded parabolic reflector, research of Signify has observed that the parabolic mirror sheet (of the parabolic reflector) may not end up in the designed shape. The largest deviation in manufacturing tolerances appear to be in the region around the vertex of the parabolic reflector, where the curvature is highest. Hence, relatively large manufacturing tolerances of the reflector may need to be considered when using the cheapest and most straightforward technology: bending of a sheet reflector. More accurate manufacturing technologies are available but at significantly higher costs. Thus, there is a clear need for a solution that does not require a strongly curved, and hence costly reflector.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an improved light-based disinfection device, which at least alleviates the problems and disadvantages mentioned above. Thereto, the invention is defined by the appended claims. Thereto, the invention provides, a lightbased disinfection device comprising: a single curved parabolic reflector comprising a focal line consisting of the focal points, a symmetry plane, a parabolic depth, and a parabolic surface area; a plurality of LED packages arranged on said focal line, wherein each LED package comprises respectively an ultraviolet LED and a pre-collimator optic; wherein the ultraviolet LED is configured to emit first ultraviolet light along an optical axis perpendicular to the symmetry plane of the single curved parabolic reflector, wherein the first ultraviolet light comprises a first angular light distribution around said optical axis; wherein the pre- collimator optic is configured to transform said first ultraviolet light into a second ultraviolet light, wherein the second ultraviolet light comprises a second angular light distribution around said optical axis; wherein the second angular light distribution is smaller than the first angular light distribution in the direction of the parabolic depth; wherein each LED package of the plurality of LED packages is configured to project the second ultraviolet light along the optical axis to only a part of the parabolic surface area.

Hence, because the pre-collimator optic transforms the first angular light distribution of the ultraviolet LED into a smaller second angular light distribution in the direction of the parabolic depth, the second ultraviolet light emitted by the LED package remains projected to only a part of the parabolic surface area, and is thereby prevented to escape the reflector as stray light. Moreover, the LED package is configured to project said second ultraviolet light along the optical axis to only a part of the parabolic surface area. The optical axis is thereby perpendicular to the symmetry plane of the single curved parabolic reflector, and the second ultraviolet light is having a limited angular light distribution compared to the first ultraviolet light emitted by the ultraviolet LED. Consequently, the LED package is enabled to project said second ultraviolet light to either parts with less curvature, or to parts away from the trim. The present invention is thereby enabling lower manufacturing cost than in former situation, as more manufacturing tolerances are occurring in the parts of the parabolic mirror with higher curvature (i.e. larger errors). The present invention is also causing less stray light (that is escaping the rim without being reflected) in the latter situation.

Hence, the present invention clearly overcomes the problems and disadvantages mentioned above.

As mentioned, the optical axis is perpendicular to the symmetry plane of the single curved parabolic reflector. Alternatively phrased, said “optical axis being perpendicular to the symmetry plane of the single curved parabolic reflector” may be the “optical axis overlapping with the latus rectum (of the parabola) of the single curved parabolic reflector”.

As mentioned, the invention provides a light-based disinfection device comprising a single curved parabolic reflector. Said single curved parabolic reflector may comprise a first parabolic reflector leg and/or a second parabolic reflector leg. Said parabolic legs may define the parabolic surface. Hence, the single curved parabolic reflector may be a halve parabola or a full parabola, or even a part of a parabola (such as for example a fraction of the parabolic shape of the first parabolic reflector). Hence, the latter phrased differently, the single curved parabolic reflector may be a single curved off-axis parabolic reflector.

Said “angular light distribution around said optical axis” is characterizing the optical axis as being a reference axis to the angular light distribution of the respectively emitted ultraviolet light. Said optical axis is thereby defined to be zero degrees, namely the zero degrees reference when considering the angular light distribution (and/or an angular range) of the emitted light. Said symmetry plane may thereby be defined to be minus 90 degrees or plus 90 degrees, for example when considering the angular light distribution in the direction of the parabolic depth, wherein the angular distribution is negative in the direction towards the vertex of the single curved parabolic reflector and positive in the direction (towards the rim) away from the vertex of the single curved parabolic reflector. The single curved parabolic reflector is elongated and curved around an axis defining the elongated direction.

Said parabolic depth is defined as a respective chord along the axis of symmetry from the vertex, through the respective focal point, to the plane of the rim of the single curved parabolic reflector. Said direction of the parabolic depth may also be defined as being the same as the direction of the axis perpendicular to the focal line and in plane with the symmetry plane. Said direction of the parabolic depth may also be defined as being the same direction as the direction of the focal length of the single curved parabolic reflector.

Said projecting the second ultraviolet light may alternatively be phrased as emitting the second ultraviolet light. In embodiments, said ultraviolet LED may be one of an UV-C LED, an UV-B LED, an UV-A LED, a Far-UV-C LED, a Near UV-C LED.

Said vertex may alternatively be phrased as apex. The LED is a Light Emitting Diode. In alternative aspects, the ultraviolet LED may be a conventional UV light source, or a laser UV light source.

In embodiments, each LED package may comprise at least one ultraviolet LED. Hence, each LED package may comprise a plurality of ultraviolet LEDs, such as at least two, or at least four. Such embodiments may render more lumen output of the lightbased disinfection device.

In an embodiment, the first angular light distribution is defined by a first angular range relative to said optical axis in the direction of the parabolic depth; wherein the second angular light distribution is defined by a second angular range relative to said optical axis in the direction of the parabolic depth; wherein the second angular range is at least a factor two smaller than the first angular range. Said ‘a factor two smaller’ may be phrased differently as ‘two times smaller’ . In further embodiments, said second angular range may be at least 90 degrees smaller than the first angular range.

Hence, the pre-collimating optic significantly narrows the first angular light distribution of the ultraviolet LED, such that the less narrow second angular light distribution may be outputted by the LED package, thereby preventing stray light and/or allowing less strict manufacturing tolerances for the parabolic reflector so as to render cheaper manufacturing options.

In an embodiment, the first angular range is between minus 90 degrees and plus 90 degrees relative to said optical axis in the direction of the parabolic depth; wherein the second angular range is between minus 40 degrees and plus 40 degrees relative to said optical axis in the direction of the parabolic depth. In an embodiment, the first angular range is between minus 90 degrees and plus 90 degrees relative to said optical axis in the direction of the parabolic depth; wherein the second angular range is between minus 25 degrees and plus 25 degrees relative to said optical axis in the direction of the parabolic depth.

Since the first angular range is between minus 90 degrees and plus 90 degrees relative to said optical axis in the direction of the parabolic depth, the selected ultraviolet LED may be different in radiation pattern, and the solution of the present invention may thereby be robust to different types of ultraviolet LEDs.

In aspects, the ultraviolet LED may comprise a cut-off distribution means, wherein the cut-off distribution means defines the first angular light distribution and the first angular range of the ultraviolet LED. Hence, for example, the first angular range being between minus 90 degrees and plus 90 degrees may be the first angular range being defined by minus 60 degrees and plus 60 degrees.

In an embodiment, the second angular light distribution and the first angular light distribution are substantially the same in the direction of the focal line. Such an embodiment may define that the pre-collimator optic is only transforming, (or: ‘collimating’) the first angular light distribution in the direction of the parabolic depth and not in the direction of the focal line (that is being perpendicular to the parabolic depth direction). This means that for a single curved parabolic reflector, each LED package may still emit a wide second angular light distribution in the elongated direction of the single curved parabolic reflector. This may render a more efficient sheet-line beam out of the parabolic reflector, while still preserving the other mentioned advantages of the present invention.

In other words, the angular distribution of the ultraviolet light in the noncurved direction of the single curved parabolic reflector is preferably not transformed, so as to maintain the widest beam in that direction

For example, in aspects, the pre-collimator optic of each LED package may be an elongated single curved parabolic reflector as well, wherein the ultraviolet LED may be arranged at the focal line or at a focal point of said elongated single curved parabolic reflector. Said elongated single curved parabolic reflector may be phrased for convenience as a second single curved parabolic reflector or a local single curved parabolic reflector. Hence, the LED package may project the second ultraviolet light as a sheet-like beam on only a part of the parabolic surface area (thereby the elongated direction of said sheet matching the elongated direction of said single curved parabolic reflector of the light-based disinfection device). Hence, a local single curved parabolic reflector (of the at least one LED package of the light-based disinfection device) is employed to project the second ultraviolet light onto the (main) single curved parabolic reflector of the light-based disinfection device.

Furthermore, said substantially the same may mean that the second angular light distribution and the first angular light distribution are no more than 45 degrees different, preferably no more than 30 degrees different, most preferably no more than 15 degrees different, in the direction of the focal line. Alternatively, the first angular light distribution and the second angular light distribution may be maximally 25% off relative to each other in the direction of the focal line.

In an embodiment, the pre-collimator optic may be concentric with the optical axis and/or rotationally symmetric around the optical axis.

In an embodiment, the pre-collimator optic may be a rotationally symmetric reflector.

In an embodiment, the pre-collimator optic may consist of a pre-collimator optic material, wherein said pre-collimator optic material comprises reflective aluminium. Alternatively, other ultraviolet reflective materials may be envisioned as the pre-collimator optic material; such as materials like for example polished stainless steel, gold, silver, copper; that are reflective to ultraviolet light and may be easy to form mechanically by e.g. pressing, bending, cutting, extruding, stamping, punching.

In an embodiment, the pre-collimator optic may be an extruded, stamped or molded compound parabolic concentrator.

In an embodiment, the pre-collimator optic may comprise a length of at most 12 millimeters, a width of at most 12 millimeters, and a height of at most 12 millimeters.

In an embodiment, the ultraviolet LED may comprise a length of at most 4 millimeter and a width of at most 4 millimeter.

As mentioned, the present invention alleviates the problem of stray light emanating from a light-based disinfection device using a reflector to render the sheet-like (or: substantially collimated) ultraviolet beam for disinfection.

More specifically, said pre-collimator optic may also be a mirror, which mirror may be arranged in the LED package next to the ultraviolet LED, on the side facing the rim of the single curved parabolic reflector (i.e. the side opposite to the vertex of the single curved parabolic reflector). Said mirror may be configured to block rays of first ultraviolet light that would otherwise escape the parabolic reflector without being reflected. Said mirror may therefore be configured to reflect said first ultraviolet light back as second ultraviolet light to the parabolic surface area (so as to get collimated by the parabolic reflector). Hence, in an embodiment, the first angular range may be between minus 90 degrees and plus 90 degrees relative to said optical axis in the direction of the parabolic depth; wherein the second angular range is between minus 90 degrees and 0 degrees relative to said optical axis in the direction of the parabolic depth. Such an embodiment defines that the second ultraviolet light, and the corresponding second angular light distribution, is projected back into the single curved parabolic reflector, with no chance to escape the parabolic reflector surface directly through the downstream opening of the parabolic reflector. Hence, the second ultraviolet light may be collimated effectively and efficiently by the single curved parabolic reflector, thereby mitigating stray light.

Hence, as partly mentioned, in an embodiment, the pre-collimator optic is a mirror, wherein the ultraviolet LED is arranged between the vertex of the single curved parabolic reflector and the mirror.

Such an embodiment may also enable the focal line of the single curved parabolic reflector to be closer to the rim of the single curved parabolic reflector. This may render a significantly more compact design of the light-based disinfection device, while still maintaining the requirements for safety (as stray light is limited / mitigated).

Hence, in an embodiment, wherein the distance of the focal line to the vertex of the single curved parabolic reflector may be at least 10 millimeters, preferably at least 15 millimeters, more preferably at least 25 millimeters.

For example, the distance of the focal line to the vertex of the single curved parabolic reflector may be 25 millimeters for a single curved parabolic reflector having a parabolic depth of 40 millimeters and/or a parabolic height of 60 millimeters. Said parabolic height being defined along the directrix (and e.g. being the total height of the parabolic reflector measured at the rim).

Said ultraviolet LED may emit initial LED light, wherein said ultraviolet LED may comprise a converting layer for converting the initial LED light into said first ultraviolet light.

In embodiments: Said LED package may further comprise a visible LED.

Said visible LED may be configured to emit visible light. Said LED package may thereby be configured to further emit (or: project) visible light along the optical axis. Said visible light may not be harmful to humans. Moreover, said pre-collimating optic may be configured to only transform said ultraviolet light into a second ultraviolet light, and not transform said visible light into the second ultraviolet light. In embodiments, the ultraviolet LED may be configured to emit said first ultraviolet light along an optical axis, wherein the optical axis is under an angle with the normal of the symmetry plane of the single curved parabolic reflector, wherein said angle is at most 30 degrees, preferably at most 20 degrees, most preferably at most 10 degrees. Hence, the LED package may be configured to project the second ultraviolet light along the optical axis to only a part of the parabolic surface, which optical axis is slightly tilted relative to the symmetry plane / symmetry axis of the parabolic reflector.

In an embodiment, the light-based disinfection device is an upper air disinfection luminaire.

Thereto, in aspects, the invention provides an upper air disinfection luminaire comprising a single curved parabolic reflector comprising a focal line consisting of the focal points, a symmetry plane, a parabolic depth, and a parabolic surface area; at least one LED package arranged on said focal line, wherein each LED package comprises an ultraviolet LED and a pre-collimator optic; wherein the ultraviolet LED is configured to emit first ultraviolet light along an optical axis perpendicular to the symmetry plane of the single curved parabolic reflector, wherein the first ultraviolet light comprises a first angular light distribution around said optical axis; wherein the pre-collimator optic is configured to transform said ultraviolet light into a second ultraviolet light, wherein the second ultraviolet light comprises a second angular light distribution around said optical axis; wherein the second angular light distribution is smaller than the first angular light distribution in the direction of the parabolic depth; wherein the LED package is configured to project the second ultraviolet light along the optical axis to only a part of the parabolic surface area. Thereby, advantages and/or embodiments applying to the light-based disinfection device according to the invention may mutatis mutandis apply to said upper air disinfection luminaire according to the invention.

It is further an object of the invention to provide an improved assembly according to the invention. Thereto, the invention provides an assembly of a single curved parabolic reflector according to the invention and a LED package according to the invention, wherein the LED package is arranged on said focal line of the single curved parabolic reflector. Thereby, advantages and/or embodiments applying to the light-based disinfection device according to the invention may mutatis mutandis apply to said assembly according to the invention. Said assembly may be phrased as an optical assembly.

In further aspects, the invention provides a light-based disinfection device comprising: a single curved parabolic reflector comprising a focal line consisting of the focal points, a symmetry plane, a parabolic depth, and a parabolic surface area; at least one LED package arranged on said focal line, wherein each LED package comprises an ultraviolet LED and a pre-collimator optic; wherein the ultraviolet LED is configured to emit first ultraviolet light along an optical axis perpendicular to the symmetry plane of the single curved parabolic reflector, wherein the first ultraviolet light comprises a first angular light distribution around said optical axis; wherein the pre-collimator optic is configured to transform said first ultraviolet light into a second ultraviolet light, wherein the second ultraviolet light comprises a second angular light distribution around said optical axis; wherein the second angular light distribution is smaller than the first angular light distribution in the direction of the parabolic depth; wherein the LED package is configured to project the second ultraviolet light along the optical axis to the parabolic surface area.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be further elucidated by means of the schematic nonlimiting drawings:

Fig. 1 depicts schematically an embodiment of a light-based disinfection device according to the invention;

Fig. 2 depicts schematically an embodiment of a light-based disinfection device according to the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Figure 1 depicts schematically, by non-limiting example, an embodiment of a light-based disinfection device 10 according to the invention. Figure 1 depicts a cross- sectional sideview. The light-based disinfection device 10 comprises a single curved parabolic reflector 11 and at least one Light Emitting Diode (LED) package 12.

The single curved parabolic reflector 11 is elongated. The single curved parabolic reflector 11 comprises a parabolic shape 1. The elongated direction is defined as the width of the single curved parabolic reflector 11. Due to said parabolic shape 1 extending in the elongated direction, said single curved parabolic reflector 11 also comprises a focal line 2. Since figure 1 depicts a cross-sectional sideview of the light-based disinfection device 10 and the single curved parabolic reflector 11 thereof, and because a focal line 2 generally consists of the focal points of a parabola / parabolic reflector, the focal line 2 is depicted in figure 1 as a focal point of the parabolic shape 1. The single curved parabolic reflector 11 further comprises a vertex 3 and a symmetry plane 4. The symmetry plane 4 crosses the vertex 3 as generally known for a parabola or parabolic shape 1. The symmetry plane 4 extends both in the elongated direction of the single curved parabolic reflector 11 (i.e. also the direction of the focal line 2) and in the direction of the focal length of the parabolic shape 1. The focal length is generally defined as the chord between the vertex 3 and the focal point 2 of a parabola.

The parabolic shape 1 of the single curved parabolic reflector 11 also comprises a parabolic depth 5. The parabolic depth 5 is defined as the respective chord extending along the symmetry plane 4 (or: the axis of symmetry) from the vertex 3, through the respective focal point 2, to the plane of the rim 6 of the single curved parabolic reflector 11. The rim 6 is the downstream edge of the single curved parabolic reflector.

The single curved parabolic reflector 11 further comprises a height 7. The height is defined and bounded by the rim 6 in the direction perpendicular to the symmetry plane 4.

The single curved parabolic reflector 11, and/or the parabolic shape 1 thereof, further comprises a parabolic surface area 8. The parabolic surface area 8 is configured to collimate rays of light emanating from the focal point 2 and/or focal line 2 of the single curved parabolic reflector 11

All in all, the single curved parabolic reflector 11 comprises - amongst others - a focal line 2 consisting of the focal points, a symmetry plane 4, a parabolic depth 5, and a parabolic surface area 8.

Still referring to figure 1, the at least one LED package 12 is arranged on said focal line 2. In the present embodiment, a plurality of LED packages 12 are arranged on said focal line 2, but due to the cross-sectional view of figure 1, only one LED package 12 is depicted in figure 1. In other examples, an array of LED packages may be envisioned arranged on said focal line 2.

A traditional LED package according to the prior art, which is arranged on such a focal line of a parabolic reflector and is emitting light with a light distribution of typically minus 90 degrees and plus 90 degrees along an optical axis, will still cope with the problem of some stray light directly escaping the parabolic reflector surface. For a LED package emitting ultraviolet light, such stray light may be hazardous to humans.

Even further, such a traditional LED package may also emit light to the highly curved regions of the parabolic shape, namely the regions close to the vertex. Therefore, very strict manufacturing tolerances are required at the highly curved regions of the parabolic shape, which may only be achieved with more expensive manufacturing technologies. This increases the cost of manufacturing a light-based disinfection device, which utilizes a single curved parabolic reflector with ultraviolet LED lighting.

The light-based disinfection device 10 according to the present invention solves both problems mentioned above with the LED package 12 arranged on the focal line 2 of the single curved parabolic reflector 11.

Namely, each LED package 12 comprises an ultraviolet LED 13 and a precollimator optic 14. Said ultraviolet LED 13 is hereby an UV-C LED, but may alternatively be an UV-A LED or UV-B LED. The pre-collimator optic 14 may enclose said ultraviolet LED 13. The ultraviolet LED 13 emits, in operation, first ultraviolet light 15 along an optical axis 9. The optical axis 9 is perpendicular to the symmetry plane 4 of the single curved parabolic reflector 11. Hence, said optical axis 9 may be along the latus rectum of the parabolic shape 1 (or: parabola).

The first ultraviolet light 15 comprises a first angular light distribution 16 around said optical axis 9. The first angular light distribution 16 is thereby defined relative to the optical axis 9, as the reference. Said optical axis 9 is thereby defined to be zero degrees, namely the zero degrees reference when considering the angular light distribution.

The first angular light distribution 16 is defined by a first angular range 16’ relative to said optical axis 9 in the direction of the parabolic depth 5. Here, as an example, the first angular range 16’ is minus 90 degrees and plus 90 degrees relative to said optical 9 in the direction of the parabolic depth 5.

Still referring to figure 1, the pre-collimator optic 14 is configured to transform said first ultraviolet light 15 into a second ultraviolet light 17. The second ultraviolet light 17 comprises a second angular light distribution 18 around said optical axis 9. The pre-collimator optic 14 is thereby an extruded compound parabolic concentrator. The pre-collimator optic 14 consists of a pre-collimator optic material, wherein said pre- collimator optic material comprises reflective aluminium. Hence, the pre-collimator optic 14 is made of reflective aluminium. The pre-collimator optic may alternatively be made of gold, copper, reflective stainless steel, silver.

The pre-collimator optic may, in alternative embodiments, be any other optic transforming the first ultraviolet light into a more narrow second ultraviolet light in the direction of the parabolic depth. The pre-collimator optic may for example be concentric with the optical axis and/or rotationally symmetric around the optical axis. Still referring to figure 1, the second angular light distribution 18 is smaller than the first angular light distribution 16 in the direction of the parabolic depth 5. More specifically, in the present embodiment, the second angular range 18’ is minus 25 degrees and plus 25 degrees relative to said optical 9 in the direction of the parabolic depth 5. Therefore, the second angular range 18’ is at least 90 degrees smaller than the first angular range 16’, namely 130 degrees smaller over the full range.

In further embodiments, not depicted, the first angular light distribution 16 and the corresponding first angular range 16’ and the second angular light distribution 18 and the corresponding second angular range 18’ is defined in the direction of the parabolic depth 5. However, in the direction perpendicular to the parabolic depth 5, which is in the direction of the focal line 2, the first angular light distribution 16 and the second angular light distribution 18 may be the same.

This means that the pre-collimating optic 14 is only transforming the first ultraviolet light 16 in the direction of the parabolic depth 5 and not the other directions like in the direction of the focal line 2. In said other directions, the second angular light distribution 18 may still be minus 90 degrees and plus 90 degrees around the optical axis 9. In other words, the angular distribution of the ultraviolet light in the non-curved direction of the single curved parabolic reflector is preferably not transformed, so as to maintain the widest beam in that direction. Yet in other alternative examples, the pre-collimating optic may transform, or collimate, said first ultraviolet light also in said direction of the focal line, alike in the direction of parabolic depth.

Still referring to figure 1, the LED package 12 projects (or: emits) in operation the second ultraviolet light 17 (having the second angular light distribution 18) along the optical axis 9 to only a part 8’of the parabolic surface area 8. Said part 8’ of the parabolic surface area 8 is not the highly curved region close to the vertex 3 of the single curved parabolic reflector 11 and its parabolic shape 1. The second ultraviolet light 17, having the more narrow second angular light distribution 18 due to the pre-collimator optic, is also not projecting said ultraviolet light 17 beyond the rim 6 of the parabolic reflector 11 without being collimated by the single curved parabolic reflector 11 first. Hence, the present invention provides a light-based disinfection device 10 that enables more safe UV disinfection at lower manufacturing cost.

In other words, the resulting ultraviolet light 17 emitted / projected by the LED package 12 is aimed at a weakly curved part 8’ of the single curved parabolic reflector 11 at the second angular distribution 18 and range 18’, so as to ensure that all light hits the reflector, and no harmful stray light can escape. This may also mitigate the need for additional safety features for a light-based disinfection device, like absorbing lamellae to block the stray light, thereby rendering an increased optical efficiency.

The second ultraviolet light, as projected (or: emitted) by the LED package along the optical axis may for example comprise a FWHM of 3.3 degrees in the direction of the parabolic depth.

Furthermore, in aspects, by non-limiting example, not particularly depicted, the ultraviolet LED may comprise a length of at most 1 millimeter and a width of at most 1 millimeter, and the pre-collimator optic may typically comprise a length of at most 4 millimeters, a width of at most 4 millimeters, and a height of at most 12 millimeters. For example, length x width x height being 3x3x10 millimeter. The width (elongation) of the single curved parabolic reflector may for example be 120 millimeters. The height of the single curved parabolic reflector may for example be 60 millimeters. Here, the focal line 2 may for example be at 15 millimeters.

In alternative aspects, the respective LED package may comprise a PCB. Said PCB may comprise the ultraviolet LED, or the ultraviolet LED and the pre-collimator optic. Said PCB may alternatively comprise a further LED, such as a visible light LED, for example a white LED or violet LED.

Figure 2 depicts schematically, by non-limiting example, an embodiment of a light-based disinfection device 20 according to the invention, which is similar to the lightbased disinfection device 10 depicted in the embodiment of figure 1, but with the at least one LED package 22 being different.

Namely, figure 2 depicts a cross-sectional sideview. The light-based disinfection device 20 comprises a single curved parabolic reflector 21. The single curved parabolic reflector 21 is identical to the single curved parabolic reflector 11 of the embodiment depicted in figure 1, and identical to its corresponding properties, such as the parabolic shape 1, the focal line 2, the vertex 3, the symmetry plane 4, the parabolic depth 5, the rim 6, the height 7, and the parabolic surface area 8.

However, as mentioned, the light-based disinfection device 20 depicted in the embodiment of figure 2 comprises a different LED package 22. Again one LED package 22 is depicted due to the side-view. The LED package 22 comprises an ultraviolet LED 23 and a pre-collimating optic 24. Here, the pre-collimating optic 24 is a mirror 24. Said mirror 24 is arranged next to the ultraviolet LED 23. More specifically, the ultraviolet LED 23 is arranged between the vertex 3 of the single curved parabolic reflector 21 and the mirror 24. The mirror 24 may alternatively be phrased as a near-die mirror due to its proximity and adjacency to the ultraviolet LED 23. The mirror may for example abut in some examples the ultraviolet LED.

Here, the ultraviolet LED 23 is similarly an UV-C LED. The ultraviolet LED 23 emits, in operation, first ultraviolet light 25 along the optical axis 9. The optical axis 9 is perpendicular to the symmetry plane 4 of the single curved parabolic reflector 21.

The first ultraviolet light 25 comprises a first angular light distribution 26 around said optical axis 9. The first angular light distribution 26 is thereby defined relative to the optical axis 9, as the reference. Said optical axis 9 is thereby defined to be zero degrees, namely the zero degrees reference when considering the angular light distribution.

The first angular light distribution 26 is defined by a first angular range 26’ relative to said optical axis 9 in the direction of the parabolic depth 5. Here, as an example, the first angular range 26’ is minus 90 degrees and plus 90 degrees relative to said optical 9 in the direction of the parabolic depth 5.

Still referring to figure 2, the pre-collimator optic 24, i.e. the mirror 24, is configured to transform said first ultraviolet light 25 into a second ultraviolet light 27. The second ultraviolet light 27 comprises a second angular light distribution 28 around said optical axis 9.

The second angular light distribution 28 is smaller than the first angular light distribution 26 in the direction of the parabolic depth 5. More specifically, in the present embodiment, the second angular range 28’ is minus 90 degrees and minus 30 degrees relative to said optical 9 in the direction of the parabolic depth 5. Therefore, the second angular range 28’ is 120 degrees smaller than the first angular range 26’ over the full range.

Still referring to figure 2, the LED package 22 projects (or: emits) in operation the second ultraviolet light 27 (having the second angular light distribution 28) along the optical axis 9 to only a part 88’of the parabolic surface area 8. Said part 88’ of the parabolic surface area 8 is clearly not projecting said ultraviolet light 27 beyond the rim 6 of the parabolic reflector 21 without being collimated by the single curved parabolic reflector 21 first, because the mirror 24 positioned on the ‘downstream’ side of the parabolic reflector 21 next to the ultraviolet LED 23 is preventing any escaping (uncollimated) stray light. Hence, the present invention provides a light-based disinfection device 20 that enables more safe UV disinfection with less stray light. The embodiment depicted in figure 2 is particularly solving the problem of stray light. Moreover, the embodiment depicted in figure 2 (characterized by the mirror) may also enable the focal line 2 of the single curved parabolic reflector 21 to be closer to the rim 6 of the single curved parabolic reflector 21. This may render a significantly more compact design of the light-based disinfection device 20, as the depth of the parabolic reflector may be shorter, while still maintaining the requirements for safety (as stray light is limited / mitigated).

All in all, considering the embodiments presented above, the present invention may eliminate the stray light generated in an upper-air disinfection system based on UV-C LEDs and a parabolic reflector by limiting the angular light distribution of the LEDs with a pre-collimator optic. The objective to provide a light-based disinfection device, which is robust for different types of UV-C LEDs (for example that also types with a wider radiation pattern can be used) may similarly be resolved. Moreover, the invention may enable a lightbased disinfection device to advantageously use a parabolic reflector that does not relies on a strong curvature (i.e. comprising manufacturing deviations in tolerances) such that consequently the parabolic reflector (and the light-based disinfection device) may be manufactured with relatively low cost.