Koito Manufacturing Company, Ltd.

A.l.m.t. Corporation

Shinichi Irisawa

Takeshi Fukuyo

Yoshitaka Ohshima

Michio Takagaki

Nobuo Ohkawai

Masakazu Nagasawa

Yasuyoshi Numajiri

Akihiro Nagata

Kunimasa Mochiduki

Hiroshi Goto

Kunio Fukai

Yukio Wakimizu

Akira Homma

Masato Harazaki

Masaya Shido

Toshiaki Tsuda

Goichi Oda

Yukihiro Onoda

Masahiro Katoh

Masaya Shidoh

Yoshihiro Mochizuki

Yonemasa Yoshida

Yoshitaka Oshima

Yoshihiro Wada

Yukihiro Yoshida

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

There is provided a mercury-free discharge bulb for a vehicle. The mercury-free discharge bulb includes an arc tube. The arc tube includes: a light-emitting portion which is formed of a ceramic tube and includes a light-emitting material and a starting xenon gas filled therein, wherein a filling pressure of the starting xenon gas from about 6 atm to about 18 atm; thin tube portions which are formed at respective ends of the light-emitting portion; and electrodes which are fixed inside the thin tube portions and which are provided in the light-emitting portion so as to face each other. The light-emitting material includes at least a sodium halide and a rare-earth metal halide excluding a scandium halide, and a difference between a vapor pressure of the sodium halide and a vapor pressure of the rare-earth metal halide under an environment of about 1000&#xb0; C. is about 10 kPa or less.

Mercury-free discharge bulb

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

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

An alloy for a lead member is used for an electric lamp having a metal/vitreous material interface. Molybdenum or tungsten serving as an electric lamp current conductor is used as a base for the lead member, wherein the molybdenum or tungsten contains titanium oxide or other oxides. Automotive bulbs use this alloy for a lead member.

Alloy for a lead member of an electric lamp and electrode structure of the electric lamp

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

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.

Mercury-free arc tube for discharge lamp unit

A method of producing an arc tube including inserting an electrode assembly in which a bent portion is formed in a lead wire into a glass tube to self-hold the electrode assembly to a predetermined position of the glass tube. After the electrode has been inserted to the predetermined position, pinch-sealing is conducted on a portion of the glass tube where the assembly is inserted. In the method, the electrode assembly is inserted into a metal guide pipe which is coaxially disposed with respect to the glass tube, to be once held into the pipe. Thereafter, the assembly may be pushed by a thin rod-like pushing member to be inserted to the predetermined position in the glass tube. One or more vertical grooves which are to be axially engaged with the bent portion of the assembly to circumferentially lock the bent portion may be formed in the inner side of the guide pipe. Using the one or more grooves, the assembly may be guided to the glass tube W without being in sliding contact with the guide pipe. Therefore, in a preferable embodiment, this prevents metal powder, which may be produced by rubbing and shaving the inner side of the guide pipe with the bent portion of the lead wire, from entering the chamber portion as a foreign matter. A holding chuck is not required to insert the assembly into the glass tube, but is used to facilitate insertion of the assembly into the guide pipe. The chuck for holding the assembly is not restricted in shape. The assembly in the guide pipe is guided to the glass tube and may be restricted by the vertical grooves to be circumferentially positioned.

Method of producing an arc tube for a discharge lamp device

A discharge lamp arc tube in which a pair of electrode assemblies each having an electrode rod, a sheet of molybdenum foil and a lead wire integrally series-connected to one another have respective molybdenum foil containing regions pinch-sealed with glass, and electrodes are disposed opposite to each other in a closed glass bulb containing a light emitting substance or the like enclosed therein. The surface of the sheet of molybdenum foil sealed at each of the pinch seal portions has a micro-asperity surface roughened by an etching treatment including oxidation and reduction, so that silica glass is closely packed in the micro-asperity of the surface of the sheet of molybdenum foil. As a result, the adhesion (mechanical bonding strength) in the interface between silica glass and molybdenum foil is improved so that foil rising is suppressed and, accordingly, the lifetime of the arc tube is extended.

Arc tube for discharge lamp and method for producing the same

An arc tube bodyand a foil such as molybdenum foilare joined with each other such that a compressive stress of 10N/mor more remains at an ordinary temperature in the arc tube bodyalong a junction surface. The compressive stress is always generated on the arc tube bodyeven if a fluctuation in the stress is caused on the junction surface by the repetition of the ON/OFF of the arc tube (or a tensile stress is caused to have a very small value even if the compressive stress and the tensile stress are alternately generated). Thus, the junction strength of both members may be increased. In one embodiment, a plurality of cracks (intercrystalline cracks) may be generated on the molybdenum foilby a high pressure acting during pinch seal, and quartz glass is caused to enter the cracks so that the junction strength of both members can be increased.

Arc tube having compressive stress and method for manufacture of an arc tube

An arc tube, which is capable of prolonging the life thereof by preventing occurrence of a leak caused from a crack of an arc-tube body, has the average surface roughness of each of outer surfacesAa andBa of tungsten electrodesA andB pinch-sealed to pinch seal portionsandon the two sides of a light-emission tube 20of an arc-tube bodyis set to be 3 &#x3bc;m or smaller. Thus, the state of pinch-sealing of the tungsten electrodesA andB to the pinch seal portionsandis brought to a state in which the two elements are engaged with small pits and projections. Therefore, great compressive stress is not left in the region adjacent to the joint surface between the pinch seal portionsandand the tungsten electrodesA andB as distinct from the conventional structure. In a case where a crack of the arc-tube bodyis formed owing to the residual compressive stress, the crack is limited to a local portion which is the region adjacent to the joint surface. As a result, the crack is not enlarged to reach the surface of the arc-tube body

Arc tube capable of preventing occurrence of leak due to cracks and manufacturing method therefore

A mercury-free arc tube having a closed glass bulb held between pinch seal portions located at opposite ends of the closed glass bulb and a pair of electrodes provided in the closed glass bulb. The closed glass bulb does not contain mercury (Hg), but contains a main light emitting, a buffer metal halide, and a starting rare gas enclosed in the closed glass bulb. The buffer metal halide includes a halide selected from halides of Ta, Th, Cu, Rb, Nb and Pd. Preferably, at least one of the halides is Ta, Cu, Rb or Nb. The halides serve as a buffer substance and a light emitting substance in substitution for the mercury, and have an ionization potential of about 5 to 8.5 eV and excitation potential of about 4.5 eV or less having emission spectrum in a visible range, and are sealed with the rare gas.

A mercury-free arc tube includes a closed glass bulb held between pinch seal portions located at opposite ends of the close glass bulb; and a pair of electrodes provided in the closed glass bulb so as to be opposite to each other. The closed glass bulb does not contain mercury but contains main light emitting metal halide (NaI and ScI ). A rare gas is enclosed in the closed glass bulb with a charged pressure set to be in a range of from 8 to 20 atmospheres. If necessary, a predetermined buffer metal halide acting as a buffer substance is enclosed in the closed glass bulb. The charged pressure of the rare gas is higher than the conventional charged pressure (6 atmospheres).

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Shizuoka, Japan

Shinichi Irisawa