Patent Description:
For reducing the risk of distributing infectious diseases in an aircraft, it is desirable to regularly disinfect surfaces within the aircraft, which are routinely contacted by passengers and/or aircraft personnel. UV light may be used as a germicidal illumination for disinfecting the surfaces within an aircraft by illumination.

<CIT> disclose systems and methods for disinfecting a populated venue/space in real-time by autonomously employing directed disinfecting light/radiation. One embodiment comprises an ultraviolet light source which may comprise coherent and incoherent light sources that disinfect surfaces of pathogens; a set of sensors collecting data correlating to characteristics of a plurality of objects and events in the space; and a controller that receives data from the set of sensors; identifies areas to be disinfected; identifies whether the ultraviolet light source has a clear line-of-sight path to irradiate the area; and sends control signals to the light source to control the application of disinfecting light to areas in the space.

<CIT> discloses a keyboard and touchpad or mouse ultraviolet treatment system with optical sensor and inclined slide is described. A proximity sensor, microcontroller firmware, and motorized mechanism allow activation of the sanitization cycle by personnel with contaminated hands without risk of additional spreading of pathogens to other personnel and patients. The inclined slide provides stability when operated on a desk, and the microcontroller and optical sensor determine the proper exposure time to compensate for lamp aging and variations in lamp output.

It would be beneficial to provide a system and a method which provide an effective framework for disinfection via UV light in an aircraft.

According to an exemplary embodiment of the invention, a system for providing and monitoring germicidal UV illumination in an interior of an aircraft comprises at least one switchable UV light source; a light detector, which is responsive to visible light and UV light and which is configured for providing sensor outputs regarding detected light; and a controller for monitoring an operational status of the at least one switchable UV light source. The controller is configured for determining the operational status of the at least one switchable UV light source by comparing a first sensor output, provided by the light detector when the at least one switchable UV light source is activated, with a second sensor output, provided by the light detector when the at least one switchable UV light source is deactivated.

According to an exemplary embodiment of the invention, a method for providing and monitoring germicidal UV illumination in an interior of an aircraft comprises detecting light, which may include visible light and UV light, within the interior of the aircraft, while at least one UV light source within the interior of the aircraft is deactivated, with a light detector providing a first sensor output; activating the at least one UV light source; detecting light, which may include visible light and UV light within the interior of the aircraft, while the at least one UV light source provided within the interior of the aircraft is activated, with the light detector providing a second sensor output; and monitoring an operational status of the at least one switchable UV light source, wherein monitoring an operational status of the at least one switchable UV light source includes comparing the first sensor output with the second sensor output.

Systems and methods providing and monitoring UV illumination in an interior of an aircraft according to exemplary embodiments of the invention allow for an efficient and reliable disinfection of surfaces within an aircraft using UV light. They may further allow for monitoring and documenting the emission of UV light. This may allow for proving that sufficient disinfection has been carried out.

Exemplary embodiments of the invention may allow for carrying out disinfection within an aircraft automatically and for adjusting the disinfection process to a potential aging and/or deterioration of the at least one UV light source, which is employed for generating the UV light.

In an embodiment, the at least one UV light source is configured for emitting UV electromagnetic radiation having a wavelength of less than <NUM>, in particular a wavelength in the range of between <NUM> and <NUM>, further in particular a wavelength in the range of between <NUM> and <NUM>. Electromagnetic radiation having a wavelength in these ranges has been found as highly efficient for disinfection.

In an embodiment, the light detector includes a photo sensor, which is sensitive to visible light, and a wavelength converting coating. The wavelength converting coating emits visible light when being excited by UV light. Such a configuration may allow for using a comparatively inexpensive photo diode, which is sensitive to visible light, as a photo sensor. Further, as the light emitted by the wavelength converting coating, when it is excited by UV light, is visible to the human eye, humans may recognized the presence of invisible UV light directly, i.e. without the assistance of a photo sensor, by sensing the visible light emitted by the wavelength converting coating.

In an embodiment, the wavelength converting coating comprises a light transmissive adhesive, in particular a translucent adhesive, which is applied to the photo sensor, and a wavelength converting substance, which emits visible light when it is excited by UV light. The light transmissive adhesive may be a silica based material, for example a silicone or a sodium silicate.

The wavelength converting substance may be applied to an outer surface of the light transmissive adhesive, in particular to an outer surface opposite to the photo sensor. Such a configuration may allow for illuminating the wavelength converting substance with UV light, without the UV light passing through the adhesive. If the UV light does not have to pass through the adhesive, there is no risk that the UV light is attenuated or even blocked by the adhesive. Further, the adhesive may be embodied to be light transmissive only to visible light, but not to UV light. This provides more options for selecting an appropriate adhesive.

In an embodiment, the light transmissive adhesive may include a thin quartz window that encapsulates the wavelength converting substance underneath.

In an embodiment, the wavelength converting substance is applied only to a portion of the outer surface of the light transmissive adhesive. This may allow visible light to pass through the portions of the light transmissive adhesive, to which no wavelength converting substance is applied, in a particularly unimpeded manner. Such a configuration may allow the photo sensor to have high sensitivity not only to light, which is emitted by the wavelength converting substance when its is excited by UV light, but also to visible light incident on the light detector.

Additionally or alternatively, the wavelength converting coating may be applied to only a portion of a light detecting surface. This may allow visible light to illuminate surface portions of the photo sensor, which are not covered by the wavelength converting coating, in a particularly unimpeded manner.

In an embodiment, the photo sensor is configured for providing spectral information about the light detected by the photo sensor. The photo sensor may in particular provide information about the intensity of the detected light as a function of the wavelength of the detected light. Providing spectral information about the light detected by the photo sensor may be a particularly effective way of distinguishing between UV light and visible light illuminating the light detector. As a result, the operation of the UV light source may be monitored very effectively and highly reliably.

In an embodiment, the photo sensor comprises a plurality of detection channels, wherein the plurality of detection channels have different sensitivities to different ranges of electromagnetic radiation. As a result, the photo sensor may be capable to provide separate intensity information for each of a plurality of ranges of electromagnetic radiation.

In an embodiment, the photo sensor is a multi-color photo sensor, wherein the plurality of detection channels have different sensitivities to different ranges of electromagnetic radiation in the range of visible light.

In an embodiment, the wavelength converting substance includes a phosphor material. The wavelength converting substance may in particular include at least one of Y<NUM>O<NUM>:Eu<NUM>+, Sr<NUM>AL<NUM>O<NUM>:Eu<NUM>+, BaMgAl<NUM>O<NUM>:Eu<NUM>+, and LaPO<NUM>:Ce<NUM>+,TB<NUM>+.

Y<NUM>O<NUM>:Eu<NUM>+, Sr<NUM>AL<NUM>O<NUM>:Eu<NUM>+, BaMgAl<NUM>O<NUM>:Eu<NUM>+, and LaPO<NUM>:Ce<NUM>+,TB<NUM>+ have been found as very suitable and efficient materials for converting UV light into visible light.

When excited by UV light, Y<NUM>O<NUM>:Eu<NUM>+ emits red light, in particular red light having wavelengths in the range of between <NUM> and <NUM>, in particular red light having wavelengths which are basically centered around <NUM>.

When excited by UV light, Sr<NUM>AL<NUM>O<NUM>:Eu<NUM>+ emits blue light, in particular blue light having wavelengths in the range of between <NUM> and <NUM>, in particular blue light having wavelengths which are basically centered around <NUM>.

When excited by UV light, BaMgAl<NUM>O<NUM>:Eu<NUM>+ emits blue light, in particular blue light having wavelengths in the range of between <NUM> and <NUM>, in particular blue light having wavelengths which are basically centered around <NUM>.

When excited by UV light, LaPO<NUM>:Ce<NUM>+,TB<NUM>+ emits green light, in particular green light having wavelengths in the range of between <NUM> and <NUM>, in particular green light having wavelengths which are basically centered around <NUM>.

In an embodiment, the wavelength converting substance includes quantum dots for converting UV light into visible light.

In an embodiment, the system is configured for and the method includes controlling the at least one switchable UV light source based on the monitoring of the operational status of the at least one switchable UV light source. Controlling the at least one switchable UV light source may in particular include adjusting an intensity of the UV light, emitted by the at least one switchable UV light source, and/or adjusting a period of time, for which the at least one switchable UV light source is activated. This may allow for adjusting the operation of the at least one switchable UV light source so that an efficient and reliable disinfection of the surfaces, which are illuminated with the UV light emitted by the UV light source, is ensured.

In an embodiment, the system is provided in a cockpit of an aircraft and it may be configured for illuminating at least one surface, which is usually touched by the pilots, with UV light for disinfection.

In an embodiment, the system is provided in a passenger cabin of an aircraft and it may be configured for illuminating at least one surface, which is usually touched by the passengers and/or cabin crew members, with UV light for disinfection. The system may, for example, be configured for illuminating the passenger seats, in particular the arm rests and/or the head rests of the passengers seats, and/or passenger service units (PSUs), which are arranged above the passenger seats, with UV light for disinfection.

In an embodiment, the system is provided in a lavatory and/or in a galley, provided within the passenger cabin of the aircraft, for disinfecting the lavatory and/or the galley, respectively. Multiple such systems may be provided in the lavatories and/ or galleys and/or seating portions of the passenger cabin.

In an embodiment, the system(s) for providing and monitoring UV illumination according to exemplary embodiments of the invention is/are activated only after the passengers and crew have left the aircraft after landing, and the system(s) is/are deactivated before new passengers start boarding the aircraft, so that no people are present within the aircraft when the system(s) is/are activated. Activating the system only when no passengers and/or crew members are present within the aircraft may prevent humans from being irradiated with UV light.

In an embodiment, system(s) provided in lavatories of the aircraft may be additionally activated during flight when the lavatories are not occupied and the doors of the lavatories are closed, so that no UV light can exit the lavatory. Systems provided in the lavatories may, for example, be activated at regular time intervals or after a predefined number of passengers have used the respective lavatory, in order to ensure hygienic conditions within the lavatories during the flight.

In an embodiment, controlling the at least one switchable UV light source includes adjusting the intensity of UV light emitted by the at least one switchable UV light source by controlling the operation of the UV light source. The intensity of UV light emitted by the at least one UV light source may, for example, be adjusted so that the intensity of the UV light is within a predefined range between a predefined minimum intensity and a predefined maximum intensity.

In an embodiment, controlling the at least one switchable UV light source includes adjusting a period of time, for which the at least one switchable UV light source is activated. The period of time, for which the at least one switchable UV light source is activated, may in particular be adjusted as a function of the detected intensity of UV light.

For example, the period of time, for which the at least one switchable UV light source is activated, may be extended when the detected UV intensity is low, and the period of time, for which the at least one switchable UV light source is activated, may be shortened when the detected UV intensity is high, in order to achieve a substantially constant disinfection effect, independent of potential changes of the intensity of the UV light. The intensity of the UV light may vary for example due to aging of the at least one UV light source, due to contamination of the UV light source, etc..

In an embodiment, the controller is configured for calculating an indication regarding a total amount of UV light, which is emitted by the at least one switchable UV light source over time, by accumulating the sensor outputs over time. The controller may further be configured for providing a confirmation signal when the indication exceeds a predefined threshold. The confirmation signal may include a visual and/or an acoustic signal.

Such a configuration may allow for indicating that an amount of UV light, which is considered as sufficient for reliably disinfecting at least one surface illuminated with the UV light, has been detected.

The confirmation signal may also be employed as a control signal, which causes the at least one switchable UV light source to be deactivated. This may allow for automatically deactivating the at least one switchable UV light source, after a sufficient amount of UV light has been emitted. In consequence, surfaces within the aircraft may be disinfected automatically without human intervention and without excessive use of UV light.

In an embodiment, the confirmation signal includes a signal which is transmitted to a board computer of the aircraft and/or a report / log signal, which allows for logging the operation of the at least one UV light source. Logging the operation of the at least one UV light source may allow for documenting that surfaces within the aircraft have been disinfected regularly and sufficiently.

Logging the operation of the at least one UV light source may further allow for monitoring the periods of operational time of the at least one UV light source needed for sufficient disinfection. An increase of the periods of operational time needed for sufficient disinfection may indicate an aging of the at least one UV light source. In consequence, an aging UV light source may be replaced in good time before it completely fails or becomes too weak for reliable disinfection.

Further exemplary embodiments of the invention are described below with respect to the accompanying drawings, wherein:.

<FIG> shows an aircraft <NUM>, in particular an air plane, in accordance with an exemplary embodiment of the invention in a schematic side view. In the exemplary embodiment shown in <FIG>, the aircraft <NUM> is a large passenger air plane, comprising a cockpit <NUM> and a passenger cabin <NUM> housing a plurality of passenger seats <NUM>. The aircraft <NUM> may be a commercial passenger air plane, a private air plane, or a military aircraft. It is also possible that the system and method according to exemplary embodiments of the invention are implemented in a rotor-craft, such as a helicopter.

Passenger service units (PSU) <NUM> are arranged above the passenger seats <NUM>.

In an exemplary configuration, in which the aircraft <NUM> comprises six passenger seats <NUM> per row (cf. <FIG>, which will be discusses in more detail further below), each row of passenger seats <NUM> may have two passenger service units <NUM> associated therewith, one passenger service unit <NUM> assigned to the passenger seats <NUM> on the left side of a center aisle <NUM> and one passenger service unit <NUM> assigned to the passenger seats <NUM> on the right side of the center aisle <NUM>.

<FIG> depicts a schematic view of an overhead passenger service unit (PSU) <NUM>, which is arranged above the passengers of a single passenger row, as it is seen from the side of a passenger sitting on a passenger seat <NUM> below the overhead passenger service unit <NUM>.

On the side, which is shown to the left in <FIG>, the overhead passenger service unit <NUM> comprises a row of three adjustable reading lights 26a-26c, which are arranged next to each other.

Six electrical switches 27a-27c, 28a-28c are provided to the right side of the reading lights 26a-26c, a respective pair of two switches 27a-27c, 28a-28c next to each of the reading lights 26a-26c. One of the switches 27a-27c of each pair is configured for switching the adjacent reading light 26a-26c, and the second switch 28a-28c of each pair is configured for triggering a signal for calling cabin service personnel.

A row of three adjacent gaspers 29a-29c is provided next to the switches 27a-27c, 28a-28c.

Adjacent to the gaspers 29a-29c is a removable cover <NUM>, which covers a cavity housing at least three oxygen masks (not shown). In the event of pressure loss within the cabin, the removable cover <NUM> will open, the oxygen masks will drop out of the cavity and each of the passengers, sitting below the overhead passenger service unit <NUM>, may grasp one of the oxygen masks. The oxygen masks will be supplied with oxygen allowing the passengers to continue to breathe normally.

On the side opposite to the gaspers 29a-29c, a grid <NUM> is formed within overhead passenger service unit <NUM>. A loudspeaker (not shown), which may be used for delivering acoustic announcements to the passengers, is arranged behind said grid <NUM>.

Next to the grid <NUM>, there is a display panel <NUM>, which may be configured for selectively showing a plurality of visual signs (not shown), such as "non smoking" or "fasten you seat belt". The display panel <NUM> may be illuminated from behind, in order to deliver visual information to the passengers sitting below the overhead passenger service unit <NUM>.

<FIG> depicts a schematic cut-open view of an aircraft <NUM> in accordance with an exemplary embodiment of the invention, depicting a passenger cabin <NUM> of the aircraft <NUM>, also referred to as aircraft passenger cabin <NUM> herein.

The aircraft passenger cabin <NUM> is equipped with a plurality of passenger seats <NUM>. The passenger seats <NUM> are arranged next to each other forming a plurality of passenger seat rows. Each passenger seat row comprises two groups of passenger seats <NUM>, respectively including three passenger seats <NUM>. The two groups of passenger seats <NUM> are separated from each other by a center aisle <NUM>, extending along a longitudinal axis A of the aircraft <NUM>.

The aircraft passenger cabin <NUM> is further equipped with four lavatories 108a-108d. In the exemplary configuration depicted in <FIG>, lavatories 108a-108d are provided at four locations within the aircraft passenger cabin <NUM>. A first lavatory 108a is located at the front portside end of the aircraft passenger cabin <NUM>, a second lavatory 108b is located at the front starboard end of the aircraft passenger cabin <NUM>, a third lavatory 108c is located at the rear portside end of the aircraft passenger cabin <NUM>, and a fourth lavatory 108d is located at the rear starboard end of the aircraft passenger cabin <NUM>. Additionally or alternatively, lavatories 108a-108d may be provided at other locations of the aircraft passenger cabin <NUM> as well.

The aircraft passenger cabin <NUM> is further equipped with a galley <NUM>, in order to allow for preparing meals and drinks for the passengers.

At least one of the lavatories 108a-108d and the galley <NUM> is provided with a system <NUM> for providing and monitoring UV illumination according to an exemplary embodiment of the invention.

In the exemplary embodiment depicted in <FIG>, each lavatory 108a-108d and the galley <NUM> are provided with a system <NUM> for providing and monitoring UV illumination, respectively. However, exemplary embodiments of the invention also include aircraft <NUM> in which only one or any subset of the lavatories 108a-108d and the galley <NUM> are provided with a system <NUM> for providing and monitoring UV illumination.

Although not explicitly depicted in <FIG>, systems <NUM> for providing and monitoring UV illumination according to exemplary embodiments of the invention may also be provided next to the passenger service units <NUM> (cf. <FIG> and <FIG>) for disinfecting said passenger service units <NUM> by illuminating the passenger service units <NUM> with UV light.

Systems <NUM> for providing and monitoring UV illumination according to exemplary embodiments may also be provided within the passenger cabin <NUM> for illuminating and disinfecting the passenger seats <NUM> located under the passenger service units <NUM>. The systems <NUM> may, for example, be integrated into the passenger service units <NUM> or arranged next to the passenger service units <NUM>.

Systems <NUM> for providing and monitoring UV illumination according to exemplary embodiments of the invention may also be provided within the cockpit <NUM> of the aircraft <NUM> for disinfecting surfaces touched by the pilots.

As UV light may be harmful to humans, in particular to the human eye, the systems <NUM> for providing and monitoring UV illumination according to exemplary embodiments provided within the passenger cabin <NUM> and/or within the cockpit <NUM> of the aircraft <NUM> may be activated only after the passengers and crew have disembarked after the flight, so that no humans are present within the aircraft <NUM>.

Systems <NUM> for providing and monitoring UV illumination according to exemplary embodiments located in the lavatories 108a-108d, however, may also be activated during flight, when the lavatories 108a-108d are not occupied and the doors of the lavatories 108a-108d are closed, so that no UV light can exit the lavatories 108a-108d. Systems <NUM> located within the lavatories 108a-108d may, for example, be activated in regular time intervals or after a predefined number of passengers have used the respective lavatory 108a-108d, in order to ensure hygienic conditions within the lavatories during the flight.

A schematic view of a system <NUM> for providing and monitoring UV illumination according to an exemplary embodiment of the invention is depicted in <FIG>.

The system <NUM> comprises at least one lighting device <NUM>, which is configured for emitting visible light for illuminating the environment of the system <NUM>, for example the lavatory 108a-108d or the galley <NUM>. In the exemplary embodiment depicted in <FIG>, two lighting devices <NUM> are shown. Each lighting device <NUM> may comprises at least one LED acting as a light source. Each lighting device <NUM> may in particular comprise a plurality of light sources 4a-4c, which are configured for emitting light of different colors. Such a configuration may allow for adjusting the color of the light, emitted by the at least one lighting device <NUM>, by varying the intensity of the light emitted by the different light sources 4a-4c. In the exemplary embodiment of <FIG>, each of the plurality of light sources 4a-4c comprises one or more LED(s).

The system <NUM> further comprises at least one switchable UV light source <NUM>, which is configured for emitting UV light when activated. The UV light emitted by the at least one UV light source <NUM> may be directed to at least one surface for disinfecting said at least one surface, using the germicidal properties of UV light. The at least one UV light source <NUM> may include at least one LED, which is configured for emitting UV light.

The UV light emitted by the at least one UV light source <NUM> may have a wavelength of less than <NUM>, in particular a wavelength in the range of between <NUM> and <NUM>, more particularly a wavelength in the range of between <NUM> and <NUM>.

The system <NUM> further comprises a light detector <NUM> and a controller <NUM>.

The light detector <NUM> is responsive to visible light and to UV light and is configured for providing sensor outputs, representing the detected light, to the controller <NUM>.

The controller <NUM> is configured for monitoring an operational status of the at least one switchable UV light source, based on sensor outputs received from the light detector <NUM>, and for selectively activating and deactivating the at least one lighting device and the at least one UV light source <NUM>.

The controller <NUM> is in particular configured for activating the at least one UV light source <NUM> and for receiving a first sensor output, provided by the light detector <NUM> while the at least one UV light source <NUM> is activated. The controller <NUM> is further configured for deactivating the at least one switchable UV light source <NUM> and for receiving a second sensor output, which is provided by the light detector <NUM> while the at least one UV light source <NUM> is deactivated.

Alternatively, the controller <NUM> may be configured for receiving a first sensor output, which is provided by the light detector <NUM> while the at least one UV light source <NUM> is deactivated; for activating the at least one switchable UV light source <NUM>; and for receiving a second sensor output, which is provided by the light detector <NUM> while the at least one UV light source <NUM> is activated.

The controller <NUM> monitors the operational status of the at least one switchable UV light source <NUM> by comparing the first and second sensor outputs with each other. The controller <NUM> is further configured for controlling the at least one switchable UV light source <NUM> based on said monitoring of the operational status of the at least one switchable UV light source <NUM>.

Details of different modes of operation will be discussed in more detail further below.

<FIG> shows a schematic cross-sectional view of a light detector <NUM>, as it may be employed in a system <NUM> according to an exemplary embodiment of the invention.

The light detector <NUM> includes a photo sensor <NUM> sensitive to visible light, which is mounted to a support <NUM>, for example to a printed circuit board <NUM>.

The photo sensor <NUM> may in particular be configured for providing spectral information about the light detected by the photo sensor <NUM>, i.e. the photo sensor <NUM> may provide information about the intensity of the detected light as a function of the wavelength of the detected light.

The photo sensor <NUM>, for example, may comprise a plurality of detection channels, with the plurality of detection channels having different sensitivities to different ranges of electromagnetic radiation, so that the photo sensor <NUM> is capable to provide separate intensity information for each range of electromagnetic radiation, respectively.

The photo sensor <NUM> may, for example, be a multi-color photo sensor, wherein the plurality of detection channels have different sensitivities to different ranges of electromagnetic radiation in the range of visible light, e.g. in the range between <NUM> and <NUM>.

In order to allow the photo sensor <NUM> to detect UV light, the photo sensor <NUM> may be at least partially covered with a wavelength converting coating <NUM>, which is configured for emitting visible light when it is excited by UV light.

In the embodiment depicted in <FIG>, the wavelength converting coating <NUM> includes a translucent adhesive <NUM>, which is applied to an upper surface of the photo sensor <NUM> on a side opposite to the support <NUM>, and a wavelength converting substance <NUM>, which is applied to a side of the adhesive <NUM> facing away from the photo sensor <NUM>.

The wavelength converting substance <NUM> may cover the upper surface of the adhesive <NUM> facing away from the photo sensor <NUM> completely. Alternatively, the wavelength converting substance <NUM> may cover the upper surface of the adhesive <NUM> only partly, in order to allow visible light to pass through portions of the translucent adhesive <NUM>, which are not covered by the wavelength converting substance <NUM>, in an unimpeded manner.

In an alternative embodiment, which is not explicitly shown in the figures, the light transmissive adhesive <NUM> may include a thin quartz window that encapsulates the wavelength converting substance <NUM> underneath.

The wavelength converting substance <NUM> may include a phosphor material, in particular at least one of Y<NUM>O<NUM>:Eu<NUM>+, Sr<NUM>AL<NUM>O<NUM>:Eu<NUM>+, BaMgAl<NUM>O<NUM>:Eu<NUM>+, and LaPO<NUM>:Ce<NUM>+,TB<NUM>+. These phosphor materials have been found as well suited for converting UV light into visible light.

The wavelength of the visible light, into which the UV light is converted, depends on the material used for the wavelength converting substance <NUM>. In other words, the wavelength of the visible light, into which the UV light is converted, may be selected by choosing the material of the wavelength converting substance <NUM>.

Y<NUM>O<NUM>:Eu<NUM>+, for example, converts UV light very efficiently into visible red light having a wavelength of approximately <NUM>. Sr<NUM>AL<NUM>O<NUM>:Eu<NUM>+ and BaMgAl<NUM>O<NUM>:Eu<NUM>+ convert UV light to visible blue light, and LaPO<NUM>:Ce<NUM>+,TB<NUM>+ emits visible green light, when it is excited by UV light.

All these materials emit a very narrow spectrum of visible light, i.e. a spectrum of visible light in which at least <NUM> % of the light is emitted within a range of wavelengths having a width of <NUM>. Providing such a narrow spectrum of visible light may allow for reliably detecting and identifying the converted visible light, which is emitted by the wavelength converting substance <NUM>, when it is excited by UV light.

Alternatively or additionally to a phosphor material, as it has been described before, the wavelength converting substance <NUM> may include quantum dots for converting the UV light, emitted by the at least one UV light source <NUM>, into visible light, which is detectable by the photo sensor <NUM>.

<FIG> illustrate examples of light intensities I, plotted on the vertical axis, as detected by the light detector <NUM> when the at least one UV light source <NUM> is switched off (<FIG>) and when the at least one UV light source <NUM> is switched on (<FIG>). The light intensities I are depicted as a function of the wavelength λ, which is plotted on the horizontal axis.

<FIG> depicts the spectral distribution of the light emitted by the at least one lighting device <NUM> comprising three peaks <NUM>, <NUM>, <NUM>, namely a first peak <NUM> centered at approximately <NUM> corresponding to blue light, a second peak <NUM> centered at approximately <NUM> corresponding to green light, and a third peak <NUM> centered at approximately <NUM> corresponding to red light.

A spectral distribution, as it is depicted in <FIG>, is detected and stored when the at least one UV light source <NUM> is deactivated. In addition to light emitted by the at least one lighting device <NUM> provided within the aircraft <NUM>, the spectral distribution may include further spectral components (not shown), which may result from external light, in particular sun light, which enters through windows into the aircraft <NUM>.

<FIG> depicts the spectral distribution of the light detected by the light detector <NUM> when the at least one UV light source <NUM> is activated and the UV light, emitted by the at least one UV light source <NUM>, is converted into visible light, in particular into red light having a wavelength spectrum centered around <NUM>, by Y<NUM>O<NUM>:Eu<NUM>+, which has been applied to the surface of the photo sensor <NUM> as the wavelength converting substance <NUM>.

The comparison of <FIG> shows that the first and second peaks <NUM>, <NUM>, corresponding to blue light and green light, do not change when the at least one UV light source <NUM> is activated. The height of the third peak <NUM>, corresponding to the intensity of detected red light, however, increases considerably when the at least one UV light source <NUM> is activated. In the examples depicted in <FIG>, the height of the third peak <NUM> almost doubles when the at least one UV light source <NUM> is activated.

This drastic increase ΔI of the detected intensity of red light allows the controller <NUM> to reliably confirm that the at least one UV light source <NUM> is activated. It further allows the controller <NUM> to determine an indication regarding the intensity of the UV light, emitted by the at least one UV light source <NUM>, from the change of the height of the third peak <NUM>.

In case a different material than Y<NUM>O<NUM>:Eu<NUM>+ is employed as the wavelength converting substance <NUM> for converting the UV light, emitted by the least one UV light source <NUM>, into visible light, the first peak <NUM> and/or the second peak <NUM>, corresponding to blue light and green light, respectively, may increase instead of or in addition to the third peak <NUM>.

In particular, if Sr<NUM>AL<NUM>O<NUM>:Eu<NUM>+ or BaMgAl<NUM>O<NUM>:Eu<NUM>+ are included in the wavelength converting substance <NUM>, the first peak <NUM> corresponding to blue light will increase, and the second peak <NUM> corresponding to green light will increase if LaPO<NUM>:Ce<NUM>+,TB<NUM>+ is included in the wavelength converting substance <NUM>.

By comparing a first sensor output, provided by the light detector <NUM> when the at least one switchable UV light source <NUM> is activated, as it its depicted in <FIG>, with a second sensor output, which is provided by the light detector <NUM> when the at least one switchable UV light source <NUM> is deactivated, as it is depicted in <FIG>, the controller <NUM> is capable to reliably determine whether the at least one switchable UV light source <NUM> has been activated. This may be true even under varying ambient light conditions. The ambient light conditions may, for example, change due to a change of external light, in particular sun light, shining into the aircraft <NUM>.

The controller <NUM> is further capable to determine an indication regarding the intensity of the UV light and to control the operation of the at least one UV light source <NUM> based on the information about the intensity of the UV light, provided by the light detector <NUM>.

Controlling the at least one switchable UV light source <NUM> may include adjusting the intensity of UV light, emitted by the at least one switchable UV light source <NUM>, by controlling the operation of the at least one UV light source <NUM>. The intensity of UV light, emitted by the at least one UV light source <NUM>, may for example be adjusted so that the intensity of the UV light exceeds a predefined minimum intensity threshold and/or so that the intensity does not exceed a predefined maximum intensity threshold.

Controlling the at least one switchable UV light source <NUM> may also include adjusting a period of time, for which the at least one switchable UV light source <NUM> is activated. The period of time, for which the at least one switchable UV light source <NUM> is activated, may in particular be changed as a function of the detected intensity of UV light.

For example, the period of time, for which the at least one switchable UV light source <NUM> is activated, may be extended when the detected UV intensity is low, and the period of time, for which the at least one switchable UV light source <NUM> is activated, may be shortened when the detected UV intensity is high. In this way, a substantially constant disinfection effect may be achieved, independent of potential changes in the intensity of the UV light, which may occur for example due to aging of the at least one UV light source <NUM>.

The controller <NUM> may, for example, be configured for calculating an indication regarding a total amount of UV light, which is emitted by the at least one switchable UV light source <NUM> over time, by accumulating the sensor outputs over time. The controller <NUM> may further be configured for providing a confirmation signal, when the indication exceeds a predefined threshold. The confirmation signal may include a visual and/or an acoustic signal. The confirmation signal may also include a control signal, which causes deactivating the at least one switchable UV light source. Such a configuration may allow for indicating that an amount of UV light, which is considered sufficient for reliably disinfecting at least one surface by illumination with UV light, has been detected. It may further allow for automatically deactivating the at least one switchable UV light source after a sufficient amount of UV light has been detected. This may allow for a reliable automatic disinfection of surfaces within the aircraft <NUM>.

Optionally, the confirmation signal may further include a signal which is transmitted to a board computer of the aircraft <NUM> and/or a log signal, which allows for logging the operation of the at least one UV light source <NUM>. Logging the operation of the at least one UV light source <NUM> may allow for documenting that surfaces within the aircraft <NUM> have been disinfected regularly and sufficiently.

Logging the operation of the at least one UV light source <NUM> may further allow for monitoring the periods of operational time of the at least one UV light source <NUM> needed for sufficient disinfection. An increase of the periods of operational time needed for sufficient disinfection may indicate an aging of the at least one UV light source <NUM>. In consequence, an aged UV light source <NUM> may be replaced in good time before it completely fails or becomes too weak for allowing a reliable disinfection.

Claim 1:
System (<NUM>) for providing and monitoring UV illumination in an interior of an aircraft (<NUM>), wherein the system (<NUM>) comprises:
- at least one switchable UV light source (<NUM>);
- a light detector (<NUM>), responsive to visible light and UV light and configured for providing sensor outputs regarding detected light;
- a controller (<NUM>) for monitoring an operational status of the at least one switchable UV light source (<NUM>), wherein the controller (<NUM>) is configured to determine the operational status of the at least one switchable UV light source (<NUM>) by comparing a first sensor output, provided by the light detector (<NUM>) when the at least one switchable UV light source (<NUM>) is activated, with a second sensor output, provided by the light detector (<NUM>) when the at least one switchable UV light source (<NUM>) is deactivated.