Contribution of the starting electrode in hot cathode type fluorescent discharge lamps

Two types of starting auxiliary electrode were used for the investigation that the hot cathode type fluorescent discharge lamps were started on the low voltage. The ring type electrode or the strip type electrode, as the starting electrode, was positioned near the 20W fluorescent lamp wall, and the starting characteristics of the discharge lamp were measured for the source frequency region between commercial frequencies and 500Hz. For commercial frequencies and 500Hz, the relation between the main restriking voltage and the ring location and also the preheating current of electrodes were obtaind. Using the strip electrode, the relation between the main restriking voltage and the frequency and also the preheating current of electrodes were obtained. When the ring electrode location was on the discharge lamp center and on its both end, the starting voltage was the minimum value and the maximum value respectively, that is it showed V-curve. Using the ring electrode, the minimum restriking voltage dropped to about 30% (100V) at commercial frequencies and about 90% (215V) at 500Hz as compared with the normal type-Using the strip electrode, the minimum restriking voltage dropped to less than about 30% (100V) at commercial frequencies and less than 50% (120V) at high frequencies as compared with the normal type. Generaly, the starting voltage decreases as the preheating current increases, but the degree of preheating current region between 300mA and 350mA is neccesary to accelerate the starting. It is thought that the effect of the starting auxiliary electrodes resultes essentially in shortening of the electrode gap. When the reflector was earthed, the starting characteristics were not affected by the earthing effect for the strip electrode, but those were made random by the earthing effect for the ring electrode. Thus, it is concluded that as the strip type and the ring type electrode can be dropped the restriking voltage of the long type discharge lamps, using those are succesful in case of the low voltage starting in frequency region between commercial frequencies and high frequencies.