FIELD

This invention relates to an ultraviolet-C (UV-C) light-emitting diode (LED) array, and in particular, to a UV-C LED array for area disinfection.

BACKGROUND

UV-C is an invisible short-wave ultraviolet light having a wavelength ranging from 100-280 nm with germicidal properties. Use of UV-C LED arrays for UV-C irradiation of air, water and surfaces for disinfection is known to be effective. However, UV-C light is potentially harmful and can cause eye injury, skin injury and even skin cancer in persons exposed to it. There is therefore a need to enhance safety when using UV-C for disinfection to minimize health risks and accidental exposure.

SUMMARY

According to a first aspect, there is provided an ultraviolet-C (UV-C) light-emitting diode (LED) array for disinfecting an area by UV-C irradiation, the UV-C LED array comprising: at least one UV-C LED configured to emit germicidal UV-C light; and at least one safety visible-spectrum LED in electrical connection with the at least one UV-C LED such that the at least one safety visible-spectrum LED emits a visible light only when and whenever the at least one UV-C LED emits the UV-C light.

The at least one UV-C LED may comprise a plurality of UV-C LEDs, wherein the plurality of UV-C LEDs are connected in series with each other, and wherein the at least one safety visible- spectrum LED is connected in series with the plurality of UV-C LEDs.

Alternatively, the at least one UV-C LED may comprise a plurality of UV-C LEDs, wherein the plurality of UV-C LEDs are connected in series with each other, and wherein the at least one safety visible-spectrum LED is connected in parallel with the plurality of UV-C LEDs.

Alternatively, the at least one UV-C LED may comprise a plurality of UV-C LEDs, wherein the plurality of UV-C LEDs are connected in series with each other, and wherein the at least one safety visible-spectrum LED is connected in parallel with one of the plurality of UV-C LEDs. Failure of any one of the plurality of UV-C LEDs may result in voltage overload and failure of the UV-C LED array when the UV-C LED array is switched on.

The at least one UV-C LED may provide continuous UV-C output when switched on.

The at least one safety visible-spectrum LED may be an illuminator LED.

Visible light emitted by the at least one safety visible-spectrum LED may visibly illuminate the area being disinfected.

The visible light emitted by the at least one safety visible-spectrum LED may be at an output of at least 10 lumens.

The visible light emitted by the at least one safety visible-spectrum LED may be a safety light at an output ranging from 10 lumens to 50 lumens.

The visible light emitted by the at least one safety visible-spectrum LED may be of a colour that is different from a usual colour of lighting of the area.

According to a second aspect, there is provided a UV-C disinfection device comprising at least one unit of the UV-C LED array of the first aspect.

The UV-C disinfection device may be mounted on a ceiling.

The UV-C disinfection device may be configured to be moveable.

BRIEF DESCRIPTION OF FIGURES

In order that the invention may be fully understood and readily put into practical effect, there shall now be described by way of non-limitative example only exemplary embodiments of the present invention, the description being with reference to the accompanying illustrative drawings.

FIG. 1 is a schematic circuit diagram of a first exemplary embodiment of the UV-C LED array. FIG. 2 is a schematic circuit diagram of a second exemplary embodiment of the UV-C LED array.

FIG. 3 is a schematic circuit diagram of a first variation of a third exemplary embodiment of the UV-C LED array.

FIG. 4 is a schematic circuit diagram of a second variation of the third exemplary embodiment of the UV-C LED array.

FIG. 5 is a schematic circuit diagram of a third variation of the third exemplary embodiment of the UV-C LED array.

DETAILED DESCRIPTION

Exemplary embodiments of a UV-C LED array 100 will be described below with reference to FIGS. 1 to 5. The same reference numerals have been used to denote the same or similar parts across the figures.

As shown in FIGS. 1 to 5, the presently disclosed UV-C LED array 100 comprises at least one UV-C LED 10 configured to emit UV-C light for disinfecting a UV-C-irradiated area, and at least one safety visible-spectrum LED 20 configured to emit visible light. The at least one safety visible-spectrum LED 20 is in electrical connection with the at least one UV-C LED 10 such that when the UV-C LED array 100 is switched on, current passes through both the at least one UV-C LED 10 and the at least one safety visible-spectrum LED 20, so that the at least one safety visible-spectrum LED 20 emits visible light at the same time that the at least one UV-C LED 10 emits germicidal UV-C light; and when the at least one UV-C LED 10 is not emitting the UV-C light (e.g., when switched off or faulty), the at least one safety visible-spectrum LED 20 is not emitting visible light. Thus, the at least one safety visible-spectrum LED 20 emits the visible light only when and whenever the at least one UV-C LED 10 emits the UV-C light. In this way, whether the at least one UV-C LED 10 is emitting UV-C light or not can be visually detected by whether the safety visible-spectrum LED 20 is emitting visible light or not respectively. When no visible light is emitted by the at least one safety visible-spectrum LED 20, it can be concluded that no UV-C light is being emitted by the at least one UV-C LED 10 and no UV-C irradiation is taking place. When the visible light is emitted by the at least one safety visible-spectrum LED 20, it can be concluded that the UV-C light is being emitted by the at least one UV-C LED 10 and UV-C irradiation is therefore occurring.

The visible light emitted by the at least one safety visible-spectrum LED 20 thus serves as a safety light and has an output of at least 10 lumens so that it at least dimly but certainly visibly illuminates the area being disinfected. In this way, persons in the vicinity who see that the area being disinfected is illuminated by the visible light emitted by the safety visible-spectrum LED 20 can thus be warned that UV-C irradiation is taking place and avoid the area being irradiated. In a manner of speaking, the present UV-C LED array 100 thus makes the invisible visible.

Notably, the safety visible-spectrum LED 20 is not an indicator LED whose emitted light can be seen only if a person looks directly at the indicator LED bulb and which typically continues to emit an indicator light whenever connected to the power mains, even when the array is switched off. Instead, the safety visible-spectrum LED 20 is an illuminator LED that emits visible light of sufficient lumens only when and whenever the UV-C LED 10 is emitting UV-C light, so that objects from which the emitted visible light is reflected can be seen. The safety visible-spectrum LED 20 is thus configured to emit a visible light that is visibly detectable by looking only at the area that is being disinfected without having to look at the safety visible-spectrum LED 20 itself.

In an exemplary embodiment, visible light emitted by the at least one safety visible-spectrum LED 20 need not be at a lumens level required for general lighting or task-lighting as no persons should be in the area when the at least one UV-C LED 10 is emitting UV-C light to disinfect the area. In the exemplary embodiment, the visible light emitted by the safety visible-spectrum LED 20 only needs to dimly illuminate the area being disinfected (e.g., at an output ranging from 10 lumens to 50 lumens) as a safety light to show that the at least one UV-C LED 10 is irradiating UV-C light; the emitted visible light need not provide general lighting or task-lighting illumination in the area.

Although the visible light emitted by the at least one safety visible-spectrum LED 20 may be of any desired colour, for greater safety, the visible light emitted by the at least one visible-spectrum LED 20 is preferably of a colour that is different from a usual colour of lighting of the area being disinfected, i.e., the emitted visible light is not a colour of light that is usually used to illuminate the area for normal use. For example, the visible light emitted by the safety visible-spectrum LED 20 may be a non-white light such as blue, green, or purple light, so that illumination of the area by the non-white light provides an immediately recognizable indication that UV-C disinfecting irradiation is taking place.

The at least one safety visible-spectrum LED 20 in the UV-C LED array 100 also serves to show whether the UV-C LED array 100 is working or not in terms of UV-C irradiation. For example, in a conventional UV-C LED array consisting of only UV-C LEDs, it is possible that the conventional UV-C LED array is switched on and assumed to be working but that no UV-C irradiation is actually taking place because one or more of the UV-C LEDs in the conventional LED array is faulty. However, in conventional UV-C LED arrays, it will not be known whether any of the UV-C LEDs in the array is faulty because UV-C light is invisible and whether the conventional UV-C LED array is working to emit UV-C light or not cannot be visually determined. Instead, whether the conventional UV-C LED array is in working condition or not can only be detected by placing a UV-C light meter in the area when the conventional UV-C LED array is switched on, in order to check whether any UV-C irradiation is coming from the switched-on conventional UV-C LED array. Thus, when using conventional UV-C LED arrays, there is in fact no immediate or ready way to tell whether UV-C irradiation is actually taking place. Thus, with conventional UV-C LED arrays, there is no certainty whether an area has indeed been disinfected after the UV-C LED array has been switched on for some time, as there is no immediate way to discern that UV-C light was indeed ever emitted by the conventional UV-C LED array even though it had been switched on.

In contrast, by including the at least one safety visible-spectrum LED 20 in the present UV-C LED array 100, it can be readily determined by visual inspection whether the present UV-C LED array 100 is working or not. For example, if the present UV-C LED array 100 is switched on but the area supposedly being disinfected is not seen to be illuminated by the visible light that should be emitted by the at least one safety visible-spectrum LED 20, it can be concluded that no UV- C irradiation is taking place despite the present UV-C LED array 100 being switched on - therefore the array 100 must be faulty and should be repaired or replaced.

In a first exemplary embodiment of the UV-C LED array 100 as shown in FIG. 1, the at least one safety visible-spectrum LED 20 is connected in series together with a plurality of UV-C LEDs 10. In this embodiment, should any one of the UV-C LED 10 fail, even if the UV-C LED array 100 is switched on, the circuit of the array 100 will be broken and the safety visible- spectrum LED 20 will not be able to emit visible light and any other UV-C LED 10 that are in working condition in the array 100 will also not be able to emit any UV-C light.

In a second exemplary embodiment of the UV-C LED array 100 as shown in FIG. 2, the at least one safety visible-spectrum LED 20 is connected in parallel with a plurality of UV-C LEDs 10, wherein the plurality of UV-C LEDs 10 are connected in series with each other. In a third exemplary embodiment of the UV-C LED array 100 as shown in FIGS. 3-5, the at least one safety visible-spectrum LED 20 is connected in parallel with a different one of a plurality of UV- C LEDs 10, wherein the plurality of UV-C LEDs 10 are connected in series with each other. In the second and third embodiments (FIGS. 2-5), should one or more of the UV-C LEDs 10 fail, this will lead to a voltage overload such that all the LEDs 10, 20 in the array 100 (including the at least one visible-spectrum LED 20) will fail and not be able to emit any light whatsoever even when the UV-C LED array 100 is switched on.

Thus, by appropriately connecting the at least one safety visible-spectrum LED 20 with the at least one UV-C LED 10 such that the at least one safety visible-spectrum LED 20 emits the visible light only when and whenever the at least one UV-C LED 10 emits UV-C light, it will not be possible for the at least one UV-C LED 10 to continue emitting UV-C light while the at least one safety visible-spectrum LED 20 is not emitting visible light. Similarly, it will also not be possible for the at least one safety visible-spectrum LED 20 to emit visible light without the at least one UV-C LED 10 emitting UV-C light. Providing the at least one visible-spectrum LED 20 with the at least one UV-C LED 10 in the present UV-C LED array 100 thus serves as a safety feature to ensure that illumination of the area by the visible light emitted by the safety visible- spectrum LED 20 is a reliable indicator that UV-C light is being emitted by the UV-C LED array 100 to disinfect the area. The safety visible-spectrum LED 20 in the present UV-C LED array 100 therefore serves as a proxy to indicate whether the at least one UV-C LED 10 in the array 100 is in working condition and also whether the at least one UV-C LED 10 is emitting UV-C light or not, thereby providing safety and also operational verification features to the present UV-C LED array 100.

In an exemplary embodiment, the at least one UV-C LED 10 is operated to provide continuous light output, and not as pulsed UV light. This allows the control circuitry of the array 100 to be simpler, so that the presently disclosed UV-C LED array 100 provides a safe and cost-effective solution for area disinfection.

Accordingly, the disclosed UV-C LED array 100 may be comprised in a UV-C disinfection device (not shown) that is provided to disinfect a designated area. In exemplary embodiments, the UV-C LED disinfection device may be configured to be mounted on a ceiling or wall, or provided on a frame, and may be fixed in place or moveable (e.g., provided on a robot), according to the specific requirements of the area to be disinfected. The UVC-LED disinfection device may comprise one or more units of the UV-C LED array 100 depending on the level of UV-C irradiation that is desired or required to disinfect the designated area.

Whilst there has been described in the foregoing description exemplary embodiments of the present invention, it will be understood by those skilled in the technology that many variations and combination in details of design, construction and/or operation may be made without departing from the present invention. For example, while FIGS. 1-5 show the UV-C LED array 100 having only one safety visible-spectrum LED 20 and a plurality of UV-C LEDs 10, other alternative embodiments and/or variations of the UV-C LED array 100 may comprise one or more UV-C LEDslO and one or more safety visible-spectrum LEDs 20.