PURPOSE: To improve the life characterstic of the lamp as well as the starting voltage characteristic of an electric discharge lamp by installing a discharge- path restricting body which restricts so that electric discharge developed across electrodes passes through the upper part of the bulb.
CONSTITUTION: After a discharge-path restricting body 4 is inserted into a bulb 1 the inner wall of which is coated with a fluorescent layer 2, a stem 6 is inserted so that the lower end of the body 4 is fitted in the elliptic groove of the stem 6. Next, the stem 6 and the bulb 1 are fused, the bulb 1 is exhausted and subjected to electrode treatment through a fine exhaust pipe. Following that, given amounts of mercury and a rare gas are charged into the bulb 1, the fine exhaust pipe is sealed off, a base 5 is affixed on the lower end of the bulb 1, and external lead-in wires are connected and fixed to pins 5a. Here, the electrode restricting body 4 protrudes toward the sides of the bulb 1 over its entire length, where, the top side of the body 4 other than the area close to the electrode is more expanded than said area close to the electrode.
ITOU HIROSHI
YAMAZAKI HITOSHI
HATSUTORI MUTSUMI
IMAI JIYUN
