PURPOSE: To reduce the extent of starting voltage and make improvements in reliability, by setting an electrode at the side nearer to the amalgam forming material installed in an edge, down to the anode, and impressing potential of the anode on the conductive material installed in the outer surface.
CONSTITUTION: Mercury and amalgam both are formed in the inner part of a glass capillary tube 9 of a stem 6, and even if a light emitting tube temperature goes up too much at the time of lighting, mercury vapor pressure in the inner part is more lowered than when a mercury simple substance is sealed in, controlling it to an optimum level from the standpoint of a lamp efficiency aspect. And, at the time of DC lighting, an electrode 2 at the side nearer to amalgam forming material 10, in paired electrodes 2 and 3, is operated as the anode, whereby a cataphoretic phenomenon of the mercuty is prevented from occurring. On the outer surface of a light emitting tube 1, there is provided with conductive material 11 in addition. At the time of lamp starting, first intermittent discharge is generated between a tip of the conductive material 11 given anode potential and the electrode 3 becoming the cathode, and then this intermittent discharge is successively spread in a direction from the electrode 3 to the electrode 2 along this conductive material 11, and finally it is shifted to arc discharge between these electrodes 2 and 3, thus a lamp glow is started with low voltage.
YAMAZAKI HARUO
AKUTSU SHUZO
