In the light of the UV lamp, tube current will rise a little, the voltage is the same, however, the current slow rise, the voltage rise faster, finally, when the stop lamp tube current, is inside the lamp mercury has been completely will be sent to gas, the performance of UV tube was fully reflected volatile. When the lights are out, due to the circuit control, the supply voltage and current of the lamp have been cut off, and all the parameters disappear, that is to say, the current and voltage of the lamp tube are gone.