PURPOSE: To carry out frost process for outer surface homogeneously and with good reproducibility by fusing aluminosilicate glass power on the outer surface of a discharge space part of an emission tube bulb.
CONSTITUTION: A pair of electrodes 3a, 3b are sealed airtight on both ends of an emission tube bulb 2 made of quartz glass, and a predetermined amount of argon, quicksilver, dysprosium iodide, neosium iodide, and cesium idodide are sealed inside. Glass powder 6 made of aluminosilicate glass, for example, whose softening point exceeds 800°C, is fused on the outer surface of a discharge space part of the bulb 2, so as to make the surface rough. As the silicate glass powder, powder of particulate size of no more than 37μm is used, which is milled in bowl along with 3% butyl acetate solution of cellulose nitrate, so as to form a suspension, in which the bulb 2 is dipped and powder is adhered to the glass outer surface, and the powder is fused by heating. Fine adjustment of concentration of frost process is facilitated while homogeneous process is carried out even for an emission tube of complicated shape, and fusion and mixture of light are thus ensured.
KITAHARA YOSHIKI
UEMURA TOMONARI
WATANABE TORU
