The UV light of your Philips Mite Cleaner only lights up when it is used on a surface. The UV light is controlled by a sensor at the bottom of the appliance. This sensor ensures that the light goes out when the appliance is 5 cm off the surface. The sensors are added for safety reasons. For this reason, you are not able to look directly into the UV light when you lift the appliance. If the UV light is switched on, the display of the appliance shows two blue bars on the side of the display.