Abstract: The invention provides an arc tube with improved chromaticity and start-up characteristics that does not contain mercury, and provides a vehicle headlamp equipped with a metal halide lamp that contains no mercury in the arc tube. Among other improvements, the evaporation of low melting point metal halides is promoted and the start-up characteristics of the arc tube are improved.

Abstract: A vehicle discharge lighting unit can include a bulb mounting slot provided in a resin base. The mounting slot has a channel diameter that fits with an outer bulb of a lamp. A flange can be provided for mounting the resin base to a reflector. A burner band mounting section of the base can extend towards the lamp along a discharge chamber direction and project within the reflector. The driver case can also be separated into a front case and a rear case. The resin base and the driver case can therefore be most appropriately shaped while also having improved dielectric strength. When either of the base or the driver case is defective, only the part that is defective needs to be replaced.

Abstract: A high pressure discharge lamp used as a light source for an automobile headlight and a method of forming the high pressure discharge lamp are disclosed. The high pressure discharge lamp includes a discharge chamber portion defining a discharge chamber filled with metal halide and rare gas, a pair of opposing electrodes, a portion of each electrode respectively projecting a predetermined distance into the discharge chamber, molybdenum foils, lead wires, and a bulb. The bulb includes a tapered portion, a sealed portion, and a sealed end having portions of a molybdenum foil, an electrode, and a lead wire disposed therein.

Abstract: A discharge lamp for an automotive vehicle including a discharge bulb and an outer cover tube for covering the discharge bulb. The discharge bulb is composed of a discharge chamber portion, a pair of seal portions for sealing both ends of the discharge chamber portion, and a pair of discharge electrodes held in respective ones of the seal portions. At the end of each seal portion adjacent to the discharge chamber portion, a taper portion is provided, which is narrowest near the discharge chamber portion, and which defines an angle with respect to a tube axis of the discharge bulb of 45 degrees or less. A curvature of a tube wall of the discharge chamber portion, is substantially constant. A ratio of the minimum thickness to the maximum thickness of the tube wall measured within that angle is between 1 and 0.8. The discharge bulb and the outer cover tube are in contact, with the portion of said discharge chamber portion having the maximum outer diameter being in contact with the outer cover tube.

Abstract: In a method for manufacturing small tubular lamps, a moving amount of a tube stock is adjusted according to a wall thickness thereof to make the stock-guide amount uniform, and the internal pressure during the stock-guide step is also adjusted so as to produce a suitable dimension of the outside diameter thereof, whereby the working amount in the succeeding step is reduced to decrease errors in dimensional tolerances, particularly in wall thickness and internal volume.