Koito Manufacturing Company, Ltd.

Michio Takagaki

Takeshi Fukuyo

Shinichi Irisawa

Akira Homma

Masaya Shido

Yoshitaka Ohshima

Masayuki Umehara

Hiroyuki Takatsuka

Yoshihiro Mochizuki

Shinya Misonou

Yukihiro Kobayakawa

Kaname Miyagishima

Nobuyuki Kasuya

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

A mercury-free vehicle discharge bulb is provided. The discharge bulb includes an arc tube a glass shroud extending in a front-rear direction to cylindrically surround the arc tube, a metal band surrounding and holding a rear end portion of the glass shroud, and an insulating plug supporting the glass shroud in a fixed manner via the metal band. A ratio S/Sof a first area Sto a second area Sis 1 to 3. The first area Sis a surface area of an outer surface of the glass shroud in a region from a circumference of the glass shroud at a position of a center of the discharge space to a front end edge of the metal band, and the second area Sis a surface area of a surface of the metal band that touches the glass shroud.

Vehicle discharge bulb

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.

A mercury free arc tube for a discharge lamp has a closed chamber filled with rare gas and a metal halide containing at least Na halide, Sc halide and In halide, and electrodes. A ratio of a filled amount of the In halide to a total filled amount of metal halide is ranging from 0.1 to 2.0 wt %. When the ratio of the charging amount of InI is 0.1 wt % or more, the chromaticity x, y of a luminescent color during a stable discharge falls within a chromaticity standard range A of white light source. When the ratio of charging amount of InI is 2.0 wt % or less, a chromaticity y minimal value of luminescence of the arc tube at the transient time is 0.29 or more, whereby purplish red color is less conspicuous and there is no fear that an emission of the arc tube is misidentified a red marker lamp.

Mercury free arc tube for a discharge lamp

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.

Automotive headlight discharge bulb

An arc tube for a discharge lamp has a closed chamber filled with rare gas and a metal halide containing at least Na halide or Sc halide, and electrodes, wherein sealing pressure of the rare gas is 0.6 MPa or more, and a sealing density of the Sc halide in the closed chamber is ranging from 1.25 to 4.70 mg/ml. In the arc tube, since the Xe gas sealing pressure slightly higher than 0.6 MPa, the pressure in the closed chamber is increased during its lightening state. Thus, reactions leading to a flicker occurrence may be accelerated. However, the flicker occurrence can be suppressed by setting the Sc halide sealing density to 4.70 mg/ml or less. Further, a luminous efficiency required for the lamp can be assured by setting the Sc halide sealing density to 1.25 mg/ml or more.

Arc tube for a discharge lamp

A mercury-free arc tube for a discharge lamp has a closed chamber filled with rare gas and a metal halide containing at least Na halide or Sc halide and electrodes disposed on both end portions of the closed chamber so as to be opposed to each other, wherein the electrode rod is stepped shape which satisfies relationship of 1.1&#x3c;A/A&#x3c;7.3, whereas Ais a cross sectional area of the electrode in a top-end side area protruded into the closed chamber and Ais a cross sectional area of the electrode in a base-end side area fixed to the end portion of the closed chamber.

Mercury-free arc tube for a discharge lamp

An arc tube for a discharge bulb is provided for use in a vehicular lighting system. The arc tube includes a closed glass bulb that is pinch-sealed at opposite ends. Inner ends of a first electrode and a second electrode extend into the closed glass bulbs from the ends of the closed glass bulb. The atmosphere inside the closed glass bulb includes a starting rare gas, a primary light-emitting metal halide, and optionally, a buffer metal halide. The distance between the inner ends of the electrodes is between about 0.3 and 1.8, and the inner diameter of the closed glass bulb at a middle portion is between about 1.5 mm and 2.7 mm. Accordingly, a stable discharge is produced using between 15 W and 30 W of power.

A mercury-free arc tube for a discharge lamp unit including a closed glass bulb and a pair of electrode rods provided in the closed glass bulb so as to be opposite to each other. The closed glass bulb does not contain mercury as in the related art arc tubes, but contains main light emitting metal halide and starting rare gas enclosed in the closed glass bulb. In accordance with necessity, predetermined buffer metal halide in place of mercury may be enclosed to suppress the lowering of the tube voltage to some extent. In addition, the tube current I is increased to make the tube voltage high. The tube current I (unit: A) and the outer diameter d (unit: mm) of each electrode rod are set to have a relationship of 1.0&#x2266;I/d&#x2266;5.0. As a result, though such an increased tube current is used, the electrode temperature is kept in optimum temperature.

Growing community of inventors

Shizuoka, Japan

Michio Takagaki