Abstract: A metal halide lamp comprises a sealed tube containing mercury vapor and halide, and electrodes extending to a center of the sealed tube, supported by sealed portions at both ends of the sealed tube. A notch extending in a direction perpendicular to an axis of the electrode is formed in each electrode. A transverse cross sectional area of a portion where the notch is formed is smaller than the transverse cross sectional area of another portions and functions as a heat dam portion for damming heat. Accordingly, temperature of a proximal portion from the heat dam portion to the support portion is lower than that of the same portion of the conventional electrode, and temperature of a distal end portion is higher than that of the same portion of the conventional electrode. Thus, formation of low-melting alloy due to reaction of the proximal portion of the electrode and the metal halide can be suppressed.

Abstract: A light irradiation device emits a visible light and an ultraviolet ray by using one light source to reduce an energy cost and simplify a mechanism. A light source 7, a first reflection mirror 8 and a second reflection mirror 9 are provided in a case 6. A radiation light ranging from an ultraviolet area to a visible light area is emitted from the light source 7. The first reflection mirror 8 is a visible light reflection mirror and the second reflection mirror 9 is an ultraviolet ray reflection mirror. Of the light emitted from the light source 7, the visible light is reflected by the first reflection mirror 8 and the ultraviolet ray passes through the first reflection mirror 8 and is reflected by the second reflection mirror 9.

Abstract: A metal halide lamp includes a quartz sealed tube having a pair of electrodes using tungsten as the base material. Argon gas, mercury, at least one kind of rare earth metal (e.g., dysprosium, holmium, thulium, neodymium, and erbium), bromine, iodine, and an alkali metal, e.g., cesium, are contained in the sealed tube. The total number of moles of bromine and iodine in the sealed tube is in excess of the number of moles of the rare earth metal. Accordingly, tungsten which is liberated from the electrode during electric discharge can be captured mainly by iodine. A reaction between silicon dioxide, which is a constituent component of the sealed tube, and tungsten is prevented, thereby preventing blackening of the tube wall of the sealed tube.

Abstract: An FIP (Formed In Place) gasket arrangement includes three hollow parts which are joined with each other in such a way as to sealingly separate the inside and outside thereof. Two of the parts have surfaces which are flush with each other and adjoin at a line extending between the inside and outside of the two parts. The remaining one of the parts has a surface joined with the surfaces of the two parts by interposing therebetween an FIP gasket. The two parts also have edges extending along the above mentioned line, one of the edges being partially chamferred to provide a chamber. The FIP gasket has a portion filling the chamber.