FIELD OF THE INVENTION

The invention concerns a light emitting device comprising a housing having a first light exit window, and at least one light source adapted for, in operation, emitting light, where a first part of light emitted by the at least one light source has a wavelength of 200- 230nm, and where a second part of light emitted by the at least one light source has a wavelength being within the UV-spectrum but different from the wavelength of the first part of light.

BACKGROUND OF THE INVENTION

UV (Ultra Violet) disinfection has become a topic of renewed interest as the demand for sterilization increases. Currently, the use of deep UV-C light with wavelengths between 200 and 230 nm is being considered for use in living spaces. UV-C light with wavelengths between 200 and 230 nm can provide a germicidal effect by deactivating viruses and killing germs, furthermore UV light with a wavelength between 200 and 230 nm has a low penetration depth in skin and eye tissue, thus preventing the light from harming people.

UV disinfection lamps used today are mostly low pressure or medium pressure Hg lamps because they emit light with wavelengths close to the peak in the germicidal effectiveness. However, the lamps also emit light harmful to the skin and eyes of people. Therefore, they can only be used in unoccupied spaces. To overcome this issue, different products have been developed for different disinfection applications, often making use of only a limited part of the emitted spectrum of the UV disinfection lamps.

To create a UV lamp that may be safely used in living space, the other wavelengths are typically absorbed in the lamp, for example by filtering away undesired wavelengths. For instance, US 2012/0199005 A1 discloses an ultraviolet lamp, and an ultraviolet-shielding member that covers at least a part of an ultraviolet emission portion of the lamp. The ultraviolet-shielding member includes an ultraviolet non-transmissive and visible light transmissive portion that blocks or absorbs ultraviolet rays. The filtering light leads to the UV lamps having a low efficiency.

Furthermore, if the UV light is absorbed, the life time of the UV lamp is dependent on the life time of the material used for UV absorption.

US2019321499 discloses a sterilizing device that includes a housing having an opening in at least one direction thereof. The housing also has a hollow portion configured to allow insertion of an object (target) including part of a human body from the opening into the hollow portion. The ultraviolet light emitted from each ultraviolet light emitting unit includes at least part of ultraviolet light having a wavelength between 190 nm and 230 nm and at least part of ultraviolet light having a wavelength between 230 nm and 237 nm, but does not include ultraviolet light having a wavelength below 190 nm and beyond 237 nm.

US2020234941 discloses an ultraviolet sterilizer that can reduce ultraviolet light in a wavelength region of 230 to 300 nm, which is harmful to the human body, and can output effective light in a wavelength region of 200 to 230 nm with high emission intensity. The ultraviolet sterilizer of the present invention is an ultraviolet sterilizer comprising: an ultraviolet light source; a lamp storage chamber for storing the ultraviolet light source; and a light guiding part for guiding light from the ultraviolet light source, in which a band pass filter for reducing ultraviolet light in a wavelength region harmful to a human body is provided.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an alternative solution for UV light emitting device with a high efficiency, where life time of the light emitting device is not gated by the life time of a UV absorption material.

These and other objects of the invention are achieved by a light emitting device comprising a housing having a first light exit window, at least one light source adapted for, in operation, emitting light, wherein a first part of light emitted by the at least one light source has a wavelength of 200-230nm, and wherein a second part of light emitted by the at least one light source has a wavelength being within the UV-spectrum but different from the wavelength of the first part of light, and a first optical component configured to transmit the first part of light to allow the first part light to be emitted through the first light exit window and reflect the second part of light away from the first light exit window.

Consequently, and in particular by providing a first optical component configured to transmit the first part of light to allow the first part light to be emitted through the first light exit window and reflect the second part of light away from the first light exit window, a high efficiency light emitting device is provided where UV-light is not unnecessarily absorbed. Furthermore, as there is no need for using UV-absorbing elements the life-time of such elements will not provide a limitation on the life-time of the light emitting device. Also, by using an optical component with a selective reflection and transmission different wavelength ranges may be directed to different areas, allowing for optimizing the use of the different wavelength ranges.

In the context of the invention a light exit window is to be interpreted as any area, volume, or material which allow light to pass through it.

The at least one light source may be any light source configured to emit light within the UV-spectrum. The at least one light source may be configured to emit light with a plurality of wave lengths, wherein a first part of light emitted by the at least one light source has a wavelength of 200-230nm, and wherein a second part of light emitted by the at least one light source has a wavelength being within the UV-spectrum but different from the wavelength of the first part of light. In some examples the light emitting device may comprise an additional light source configured to emit light within the visible spectrum. The at least one light source may be directional light source configured to emit light in a predetermined direction. The at least one light source may be a uniform light source configured to uniformly emit light from the at least one light source.

In the context of the invention the UV-spectrum comprises any electromagnetic radiation with a wavelength from 10 nm to 400 nm.

The first optical component may be a reflector configured to reflect the second part of light and transmit the first part of light. In an embodiment, only light transmitted by the first optical component may exit the housing through the first light exit window. In an embodiment, wherein the light emitting device comprise an additional light source configured to emit light within the visible spectrum, the first optical component may be further configured to transmit light within the visible spectrum.

In an embodiment the at least one light source is at least one UV light source, and wherein the first part of light is UV-C light and the second part of light is at least one of UV-B, UV-A , and UV-C light .

Consequently, both the first part of light and the second part of light may be light with a high germicidal effect, thus further facilitating the use of the light emitting device for sterilizing purposes.

In an embodiment an interior of the housing is configured to reflect UV light incident on the interior of the housing. Consequently, UV light not transmitted by the first optical component is reflected within the housing. The UV light reflected within the housing may be used for sterilizing an interior space defined by the housing.

The interior of the housing may be provided with an optical coating for reflecting incident UV light. The interior of the housing may be provided with an optical component for reflecting incident UV light.

In an embodiment the first optical component is arranged at or defines at least a part of the first light exit window.

Consequently, it is facilitated that only the first part of light is emitted through the first light exit window, while the second part of light is reflected away from the first light exit window. In some embodiments the first optical component fully defines the first light exit window.

In an embodiment the light emitting device further comprises a second optical component, where the second optical component is configured to reflect the first part of light and transmit the second part of light.

Consequently, a higher control of light emitted by the at least one light source is allowed, as the first optical component may be configured to reflect the second part of light in a first direction, and the second optical component may be configured to reflect the first part of light in a second direction.

In an embodiment the first optical component comprises a substrate and a coating, wherein the substrate is made from any one or more of fused silica, quartz, sapphire, CaF2 and MgF2 _, and wherein the coating is a multilayer stack comprising one or more layers of S1O2 and one or more layers of HfCh.

Consequently, an interference filter is provided which can be adjusted to reflect and transmit specific spectrums of light. The applicant has found that providing a multilayer stack as described above an optical component is achieved which is UV-reflective for most electromagnetic radiation within the UV-spectrum, while exhibiting a high transmission rate for UV-light with a wavelength of 200-230nm.

Preferably, the layers within the multilayer stack has a thickness of 10-300 nm.

Preferably, the layers within the multilayer stacks alternates between layers with a high and a low refractive index.

The fused silica, quartz, sapphire, CaF2 and MgF2 are UV transparent and thus suitable to act as a substrate for the coating. In an embodiment the second optical component is arranged in the housing. Alternatively, the second optical component forms at least one surface of the housing.

Having the second optical component arranged within the housing may protect the second optical component from contaminants, e.g. dust, moisture, or volatile compounds. Having the second optical component forming a surface of the housing may allow for a compact light emitting device, as additional space for accommodating the second optical component is not required.

In an embodiment the first optical component is arranged in the housing. Alternatively, the first optical component forms at least one surface of the housing.

Having the first optical component arranged within the housing may protect the first optical component from contaminants, e.g. dust, moisture, or volatile compounds. Having the first optical component forming a surface of the housing may allow for a compact light emitting device, as additional space for accommodating the first optical component is not required.

The housing may be formed with any geometrical shape. The housing may be formed as a box, where one side of the box may act as a first light exit window from where light emitted by the at least one light source can escape the housing. The housing m may also be formed, at least partially by one or more of the first optical element and, where provided, the second optical element.

In an example, the light emitting device may further comprise at least one vent for facilitating an air flow through the housing.

Consequently, the full spectrum of light emitted by the at least one light source is used for sterilization, as both the first part of light and the second part of light may be used for sterilizing the air present in the housing.

The vent may be provided as an opening in the housing.

In a further example the vent may be configured to facilitate an air exchange between an interior of the housing and an exterior of the housing.

Consequently, the light emitting device may use the full spectrum emitted by the at least one light source for sterilizing air in a setting in which the light emitting device is arranged. The vent may be provided with a fan further facilitating an air exchange between an interior of the housing and an exterior of the housing.

In an embodiment the light emitting device further comprises a second light exit window for emitting the second part of light. Consequently, both the first part of light and part of light may be emitted for sterilization purposes. Light emitted from the first light exit window may be emitted in direction differing from that of light emitted from the second light exit window. The first light exit window may be oriented to direct light towards a room in which the light emitting device is installed, while the second light exit window may be oriented to direct light towards a ceiling or a wall of the room in which the light emitting device is installed.

In an embodiment the first light exit window is oriented to direct light exiting the first light exit window in a first direction, and the second light exit window is oriented to direct light exiting the second light exit window in a second direction, wherein light exiting the first light exit window does not overlap with light exiting the second light exit window.

In an embodiment the first light exit window is oriented to direct light exiting the first light exit window in a first direction, and the second light exit window is oriented to direct light exiting the second light exit window in a second direction, where there is an angle of at least 90 degrees between the first direction and the second direction.

In an embodiment the first optical component is a first beam shaping element.

Consequently, a higher control of the direction in which the second part of light is emitted is achieved. Furthermore, the first beam shaping element may help in focusing the second part of light in a specific direction. The first beam shaping element may be configured to reflect the second part of light in the second direction towards the second light exit window.

In an embodiment the second optical component is configured to reflect the first part of light toward the first light exit window and transmit the second part of light to allow the second part light to be emitted through the second light exit window.

Consequently, the first part of light is controlled towards the first light exit window and the second part of light is controlled towards the second light exit window.

In an embodiment the second optical component is a second beam shaping element.

Consequently, a higher control of the direction in which the first part of light is emitted in is achieved. The second beam shaping element may be configured to reflect the first part of light in a first direction towards the second light exit window.

The present invention further relates to a luminaire comprising a light emitting device according to the invention. This luminaire may also be a consumer product or a professional product with a built-in or integrated light emitting device according to the invention. It is noted that the invention relates to all possible combinations of features recited in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiments of the invention.

Fig. l is a graph depicting the emitted light intensity for a prior art UV-lamp in a filtered and non-filtered condition.

Fig. 2 is a schematic cross-sectional drawing of a light emitting device according to a first embodiment of the invention.

Fig. 3 is a schematic cross-sectional drawing of a light emitting device according to a second embodiment of the invention.

As illustrated in the figures, the sizes of layers and regions are exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of embodiments of the present invention. Like reference numerals refer to like elements throughout.

DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

Referring initially to Fig. 1, a graph 1 depicting the emitted light intensity for a prior art UV-lamp in a filtered and non-filtered condition is shown. Along the first axis of the graph is wavelength in nanometers (nm), and along the second axis is intensity in arbitrary units. The prior art UV-lamp is a KrBr excimer lamp. As is clearly seen for the unfiltered UV-lamp (large graph) is that a wide spectrum of light is emitted from the UV-lamp. Even though the largest peak intensity is seen at around 205 nm, large peaks are still present at 290 nm. As mentioned previously UV light with a wavelength between 200 and 230 nm has a low penetration depth in skin and eye tissue, thus preventing the light from harming people. However, a large part of light emitted by the KrBr excimer lamp is outside of the range of 200 to 230nm. UV-light outside this range is harmful to people, thus preventing the use of the unfiltered KrBr excimer lamp in living spaces. Consequently, to overcome this issue and to allow the use of KrBr excimer lamp in living spaces, the light emitted by the KrBr excimer lamp is filtered. The result is shown in the insert in Fig. 1. Filtering the light allows for only UV-light within the 200-230 nm spectrum to be emitted. Consequently, allowing for the use of the KrBr excimer lamp in living spaces. However, by filtering the emitted light a loss of efficiency is caused. Also, the full germicidal potential of the UV lamp is not utilized.

Referring now to Fig. 2, a schematic drawing of a light emitting device 20 according to a first embodiment of the invention is shown in a cross-sectional view. The light emitting device 20 comprises a housing 21 having a first light exit window 22. The housing 21 in the shown embodiment is formed as a box. The housing 21 is formed with an interior surface 211 and an exterior surface 212. The first light exit window 22 is formed in a side of the housing 21. The first light exit window 22 allows light emitted within the housing 21 to exit the housing 21.

Arranged in the housing 21 is a light source 23. The light source 23 is adapted for, in operation, emitting light. A first part of light 231 emitted by the at least one light source 23 has a wavelength of 200-230 nm. A second part of light 232 emitted by the at least one light source 23 has a wavelength being within the UV-spectrum but different from the wavelength of the first part of light 231. The light source 23 is an omnidirectional light source 23, i.e. it is configured to emit light in all directions away from the light source 23.

The light emitting device 20 further comprises a first optical component 24. The first optical component 24 forms part of the housing 21. In the shown embodiment the first optical component 24 fully defines the first light exit window 22 of the housing 21. The first optical component 24 is configured to transmit the first part of light 231 to allow the first part of light 231 to be emitted through the first light exit window 22. The first optical component 24 is further configured to reflect the second part of light 232 away from the first light exit window 22. Having the first optical component 24 fully forming the first light exit window 22 obstructs the second part of light 232 from exiting the housing 21 through the first light exit window 24. The first optical component 24 comprises a substrate and a coating. The substrate is made from any one or more of fused silica, quartz, sapphire, CaF2 and MgF2. The coating is a multilayer stack comprising one or more layers of SiCk and one or more layers of HfCk.

The first optical component 24 is thus formed as an interference filter.

The light emitting device 20 further comprises a second optical component 25. The second optical component 25 is configured to reflect the first part of light 231. The second optical component 25 is further configured to transmit the second part of light 232. The second optical component 25 is arranged in the housing 21. In the shown embodiment, the second optical component 25 is formed with a parabolic shape at least partly enclosing the at least one light source 23. The parabolic shape may facilitate collimation of light being reflected by the second optical light component 25. In the shown embodiment the second optical component 25 is a beam shaping element. The second optical component 25 is configured and arranged to reflect the first part of light 231 toward the first light exit window 22. Consequently, the second optical component 25 directs the first part of light 231 towards the first optical component 24.

In the shown embodiment the interior surface 211 of the housing 21 is configured to reflect UV light incident on the interior surface 211. As the housing 21 only has a single light exit window 22 which reflects the second part of light 232, and the interior surface 211 of the housing 21 also reflects the second part of light 232, the second part of light 232 is circulated within the housing 21. The circulation of the second part of light 232 helps sterilizing an interior of the housing 21.

The light emitting device 20 further comprises a vent 26. The vent 26 is provided in a side of the housing 21. The vent 26 facilitates an air exchange between an interior of the housing 21 and an exterior of the housing 21. The vent 26 may have a synergistic effect with the circulated second part of light 232, as the second part of light 232 may sterilize air within the housing 21, and the vent 26 may then be configured to let out the sterilize air and draw in non-sterilized air.

Referring now to Fig. 3, a schematic drawing of a light emitting device 30 according to a second embodiment of the invention is shown in a cross-sectional view. The light emitting device 30 comprises at least one light source 33 adapted for, in operation, emitting light. A first part of light 331 emitted by the at least one light source 33 has a wavelength of 200-230 nm. A second part of light 332 emitted by the at least one light source 33 has a wavelength being within the UV-spectrum but different from the wavelength of the first part of light 331.

The light emitting device 30 further comprises a housing and a first optical component 34. The first optical component 34 forms part of the housing. The light emitting device 30 further comprises a second optical component 35. The second optical component 35 also forms part of the housing. Thus, in this embodiment, the housing is formed at least partly by the first optical component 34 and the second optical component 35. The light source 33 is arranged inside the housing. In the shown embodiment the first optical component 34 fully defines the first light exit window 32 of the housing. The first optical component 34 is configured to transmit the first part of light 331 to allow the first part light 331 to be emitted through the first light exit window 32. The first optical component 34 is further configured to reflect the second part of light 332 away from the first light exit window 32. In the shown embodiment, the first optical component 34 is formed with a parabolic shape at least partly enclosing the at least one light source 33. The parabolic shape may facilitate collimation of light being reflected by the first optical light component 34. In the shown embodiment the first optical component 34 is a beam shaping element. The first optical component 34 is configured to reflect the second part of light 332 toward a second light exit window 36.

It is noted that other shapes of reflectors are also possible, such as a combination of two parabolic shapes used to create an intensity distribution with two peaks in different directions, which is advantageous for even illumination of a rectangular area, or elliptical reflectors or free-shape reflectors. In any event, however, the reflector is preferably a trough shape for elongated, tubular lamps, and a surface of revolution for a spherical or point-like source.

The second optical component 35 is configured to reflect the first part of light 331. The second optical component 35 is further configured to transmit the second part of light 332. In the shown embodiment the second optical component 35 fully defines the second light exit window 36 of the housing. Having the second optical component 35 fully forming the second light exit window 36 obstructs the first part of light 331 from exiting the housing through the second light exit window 36. The second optical component 35 is formed with a parabolic shape at least partly enclosing the at least one light source 33. The parabolic shape may facilitate collimation of light being reflected by the second optical light component 35. In the shown embodiment the second optical component 35 is a beam shaping element. The second optical component 35 is configured to reflect the first part of light 331 toward the first light exit window 32.

Having both the first optical component 34 and the second optical component 35 provided with parabolic shape may facilitate the collimation of the first part of light and the second part of light. Furthermore, the parabolic shapes may be oriented to collimate the first part of light and the second part of light in desired directions. Preferably, the first part of light is collimated in a first direction by the first light component 34 and the second part of light is collimated in a second direction by the second light component 35. In the shown embodiment the housing of the light emitting device 30 is defined by the first optical component 34 and the second optical component 35. Furthermore, the first optical component 34 defines the first light exit window 32, and the second optical component defines the second light exit window 36. An imaginary center plane P intersecting the light source 33 may be defined. In the shown embodiment an exterior of the first light exit window 32 faces towards an area or volume on a first side 5 of the imaginary center plane P, and an exterior of the second light exit window 36 faces towards an area or volume on a second side 4 of the imaginary center plane P. The first side 5 of the imaginary center plane P is opposed to the second side 4 of the imaginary center plane P. Thus, the first part of light 331 reflected by the second optical component 35 is reflected towards the area or volume on the first side 5 of the imaginary center plane P. Likewise, the second part of light 332 transmitted by the second optical component 35 and reflected by the first optical component 34 is reflected towards the area or volume on the second side 4 of the imaginary center plane P. The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.