Abstract: An electric discharge lamp apparatus which incorporates an arc tube 10 structured such that an enclosed glass bulb 12 of an arc tube body 11 is enclosed in an ultraviolet-ray shielding globe 20 and having a front end which is supported by a metal lead support 36 forwards extending from an insulating plug 30 provided with a focusing ring 34 and made of synthetic resin and which has a structure that a rear end of the globe 20 of the arc tube 10 is supported by a metal support member 50 secured to the insulating plug 30, wherein the metal support member 50 is constituted by a metal base plate 51 secured to the insulating plug 30 and forming a reference plane f2 running parallel to the focusing ring 34 on the front surface of the insulating plug and a metal vertically-holding member 60 (a slide plate 61 and an arc-tube holding band 71) integrally joined to the metal base plate 51 and arranged to vertically hold an electrically-discharge axis L of the held arc tube 10 with respect to reference plane f2 of the meta

Abstract: An electric discharge lamp apparatus incorporates: a metal lead support 36 which projects over the front surface of an insulating plug 30 made of synthetic resin, which supports the leading end of an arc tube 10 and which serves as a passage for electric power arranged to be supplied to the arc tube 10; and an insulating sleeve 38 which is made of ceramics formed into a pipe shape and through which the lead support 36 is inserted, wherein a predetermined gap S2 is provided between the insulating sleeve 38 and the lead support 36. Thus, insertion of the lead support 36 into the insulating sleeve 38 can easily be performed, and a dimension error of the insulating sleeve 38 can be absorbed. Since a bent portions 36a is provided for a portion of the lead support 36 into which the insulating sleeve is inserted, the insulating sleeve 38 and the lead support 36 can hermetically integrated with each other. Thus, rattle of the insulating sleeve 38 with respect to the lead support 36 can be prevented.

Abstract: An insulating plug for an electric discharge lamp apparatus, includes: a front portion includes an outer cylindrical portion and an inner cylindrical portion, the inner cylindrical portion having a substantially unique thickness and an opening to receive an arc tube of an electric discharge lamp; a focusing ring extending from the outer cylindrical portion of the front portion; and a rear portion having a rear-end cylindrical portion and a center portion. The front portion, the focusing ring and the rear portion are integrally molded by injecting a synthetic resin into a mold from a gate of the mold, the gate facing the rear-end cylindrical portion of the rear porition of the insulating plug. Furthermore, the electric discharge lamp apparatus in which an arc tube is inserted into the opening of the insulating plug described above.

Abstract: An arc tube for a discharge lamp unit which emits light which is suitable in luminous flux, color temperature, and chromaticity. The arc tube is composed of a closed glass ball in which electrodes confront one another and which is sealingly charged with light emitting materials, namely, mercury and a metal iodide of NaI and ScI.sub.3 groups together with Xe inert gas. In accordance with the invention, the closed glass ball has a volume of 20 to 50 .mu.l, the density of the mercury in the closed glass ball is in a range of 2.times.10.sup.-2 to 4.times.10.sup.-2 mg/.mu.l, the density of the metal iodide is in a range of 6.times.10.sup.-3 to 12.times.10.sup.-3 mg/.mu.l, and the charged Xe gas pressure is 3 to 6 atm. These ranges make it possible to readily manufacture on a large scale arc tubes which are substantially equal in performance, being substantially uniform in tube voltage, luminous flux, color temperature and chromaticity.