A study on the influence of operating circuit on the position of emission point of fluorescent lamp

High efficiency fluorescent lamp systems driven by high frequency are very popular for general lighting. Therefore it is very beneficial to be able to predict the lamp's life before the lamp dying, because people can buy a new lamp just before the lamp dying and need not have stocks. In order to judge the lifetime of a lamp it is very useful to know where the emission point is on the electrode filament. With regard to a method for grasping the emission point, it has been reported that the distance from the emission point to the end of the filament can be calculated by measuring the voltage across the filament (Vf in Fig.1) and the currents flowing in both ends of the filament (I 1 , I 2 in Fig.1)1. The distance from the emission point to the end of the filament can be expressed by R 1 , L 1 (or R 2 , L 2 ) in Fig.1. The values of R 1 , L 1 , R 2 and L 2 can be gotten when in the equation (1) is minimum.