An ultraviolet (UV) lighting system may for example be used for disinfection, curing of resins and many other applications. Most such UV lighting system comprises an UV light source using mercury as one of the active components. Alternatives exist, such as using costly Excimer lamps or possibly using UV LEDs. However, modern UV LEDs struggle with emission of UV light below 350 nm.
A further alternative to mercury based UV lighting is the use of field emission light source technology. Field emission is a phenomenon that occurs when a very high electric field is applied proximate to the surface of a conducting material. This field will give electrons enough energy such that electrons are emitted from the material.
An example of a field emission light source that may be adapted for UV light emission is disclosed in U.S. Pat. No. 9,288,885. In U.S. Pat. No. 9,288,885 a cathode is arranged in an evacuated chamber, having for example glass walls, wherein the chamber on its inside is coated with an anode electrically conductive layer. Furthermore, a light emitting layer is deposited on the anode. When a high enough potential difference is applied, between the cathode and the anode conductive layer, creating high enough electrical field strength, electrons are emitted from the cathode, and accelerated towards the anode. As the electrons strike the light emitting layer, typically comprising a light powder for example comprising a phosphor, will emit photons, a process referred to as cathodoluminescence. U.S. Pat. No. 9,288,885 discloses that the light emitting by the field emission light source preferably is white light but that also UV light may be emitted.
Even though U.S. Pat. No. 9,288,885 provides an interesting and alternative approach to mercury based UV lighting, no solution is given as how to achieve efficient UV light emission also below 350 nm. Thus, there is seems to be a need for further improvements in regards to UV lighting using field emission light source technology, specifically for implementations where UV light emission below 350 nm.