Koito Manufacturing Company, Ltd.

Akira Homma

Takeshi Fukuyo

Michio Takagaki

Shinichi Irisawa

Masato Harazaki

Yoshihiro Mochizuki

Shinya Misonou

In a mercury free arc tube provided with a sealed glass chamber in which at least metallic halide for main light emission is sealed as well as rare gas by pinch-sealing both end openings of a glass tube and electrode bars are opposite to each other, the tip of a region projecting into the sealed glass chamber of each the electrode bars is formed of a single crystal. Owing to repetition of ON/OFF of the arc tube, the crystal at the tip of the electrode bar grows but the shape of the electrode end face formed of the single crystal remains unchanged. Further, even if the tip of the electrode bar is gradually consumed by thermal load acting on the tip of the electrode bar, the entire shape of the electrode end face is consumed nearly uniformly so that decline of the luminescent spot does not occur during discharging.

Arc tube for discharge lamp device

An arc tube for a discharge bulb includes: an electrode assembly that has an electrode bar and a molybdenum foil, wherein an overlapping portion of an end portion of the electrode bar and a molybdenum foil is joined by spot welding; a pinch seal portion that seals a part of the electrode assembly, the part including at least the molybdenum foil; and a closed glass bulb, into which a tip of the electrode bar protrudes, the closed glass bulb forming a discharge light-emitting portion, wherein the size of a recess, which is a weld mark, in the molybdenum foil on the side opposite to a joint portion, at which the molybdenum foil and the electrode bar are joined with each other, is within a range from 0.07 mmto 0.25 mm.

Arc tube for discharge bulb and discharge bulb including the same

A mercury-free arc tube for a discharge lamp unit including a closed glass bulb in which main light emitting substances of NaI, ScI, and ScBrand buffer substances of InI and ZnIare enclosed together with Xe gas, and wherein an amount of enclosed ScBris in a range of about 5 wt % to about 24 wt % relative to a total weight of the substances enclosed in the closed glass bulb. The mercury-free arc tube may also include a shroud glass tube, which is surrounds the closed glass bulb and a pair of electrodes, which are disposed to be opposed to each other in the closed glass bulb.

Mercury-free arc tube for discharge lamp unit

In a mercury-free arc tube, regions including molybdenum foilsof electrode assemblies each of which is formed by connecting and integrating an electrode, a molybdenum foil, and a lead wire, are pinch-sealed where the electrodeprojects inside a closed glass bulb, which encloses luminescent substances, etc. The molybdenum foilis doped with or coated with TiOin the form of discontinuous lands and subjected to surface roughening by etching including oxidation and reduction. TiOparticles or a TiOlayer exposed on the rough surfaceof the molybdenum foilincreases chemical joining strength to glass and makes deeper, more complicated minute unevennesson the molybdenum foil surface to increase the mechanical joining strength to glass, so that even when a heat stress occurs at the interface between the molybdenum foil and glass in the pinch-sealed portion, foil floating does not occur.

Mercury-free arc tube for discharge lamp device and method for manufacturing the same

A discharge bulb is provided. The discharge bulb includes an arc tube, a glass shroud cylindrically surrounding the arc tube, and an insulated plug fixedly supporting an end portion of the glass shroud. The arc tube includes a light generating portion having a discharge space therein, a first pinch seal portion and a second pinch seal portion disposed on respective sides of the light generating portion, a first electrode rod protruding into the discharge space from the first pinch seal portion, and a second electrode rod protruding into the discharge space from the second pinch seal portion so as to be opposed to the first electrode rod. The discharge space contains a rare gas and a metal halide, but does not contain mercury. The first electrode is made of thoriated tungsten, and the second electrode rod is made of pure tungsten.

Discharge bulb

A mercury-free arc tube for a discharge-lamp device having a sealed glass chamber with at least metallic halide for main light emission and rare gas. Both end openings of a glass tube are pinch-sealed and electrode bars are provided so as to oppose to each other. Each electrode bar has such a concentric stepped shape that a tip side region is thicker than a base side region, the volume V of an electrode embedded region is from 0.25 to 0.42 mmand the total volume of the electrode bar is from 0.4 to 0.6 mm.

The arc tube is provided with a mercury-free arc tube main body that has a discharge light-emitting portion (closed glass sphere), and a cylindrical shroud glass tube that is airtightly integrated with the arc tube main body. In the mercury-free arc tube in which an inert gas is sealed in the shroud glass tube that surrounds the closed glass sphere, in the shroud glass tube, the adjustment is made so as to satisfy the light flux and the life span with respect to the pressure X (atmospheric pressure) of a rare gas sealed in the closed glass sphere, and an amount M (mg/ml) of sealed metal halide.

Mercury-free arc tube for discharge bulb

In a mercury-free arc tube, electrodes are configured by electrode rods heat-treated at 1,200 to 2,200&#xb0; C. in a vacuum atmosphere, and which have a thickness of 0.3 mm or more. The size (radius R) of a residual compression strain layer formed around the electrode rod is set to be &#xbc; or less of the width D of the pinch seal portion. A glass layer outside the residual compression strain layer is thickened, thereby enhancing the strength of the pinch seal portion.

ARC tube discharge lamp with compression strain layer

In an arc tube for discharge lamp, an electrode assembly is formed by integrally joining an electrode rod, a molybdenum foil, and a molybdenum lead wire. The electrode assembly is sealed into pinch seal portions located at both ends of a glass tube. The electrode assembly, before being pinch-sealed into the pinch seal portions, receives vacuum heat treatment at 200 to 800&#xb0; C. Hereby, the water content of the assembly is adjusted to 10 ppm or less, and desirably to 3 ppm less and an oxide film attached to the surface of the electrode assembly is removed. Therefore, the quantity of impurity (water or gas) enclosed in the closed glass bulb is very small, so that it is possible to provide an arc tube in which the flicker is not produced, luminous flux of 3000 lm or more is obtained, and starting voltage can be lowered to about 15 kV.

Arc tube of discharge lamp having electrode assemblies receiving vacuum heat treatment and method of manufacturing of arc tube

A discharge bulb is provided with an arc tube main body in which an arc tube having a discharge light emitting portion (a hermetically sealed glass envelope) where electrodes are provided in such a manner as to face each other is enclosed in a cylindrical shroud glass tube. The discharge bulb is configured so that a light distribution pattern having a predetermined cut-off line is formed by light intercepting portions (light intercepting films) and a light distribution control reflector. A frost treatment is applied to only a light emitting area on an outer surface of the shroud glass tube which corresponds to an area along the cut-off line in the light distribution pattern.

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Shizuoka, Japan

Akira Homma