Koito Manufacturing Company, Ltd.

Yoshitaka Ohshima

Shinichi Irisawa

Takeshi Fukuyo

Nobuo Ohkawai

Akihiro Nagata

Yasuyoshi Numajiri

Masato Harazaki

Kunimasa Mochiduki

Hiroshi Goto

Masaya Shido

Michio Takagaki

Masakazu Nagasawa

Masayuki Umehara

Yukihiro Kobayakawa

Nobuyuki Kasuya

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

Arc tube including step-down plane portions in pinch seal area

A method of manufacturing an arc tube having a light emitting tube portion, a first pinch seal portion, and a second pinch seal portion, all formed on a quartz glass tube. The first and second pinch seal portions are disposed on both sides of the light emitting tube portion. The quartz glass is provided almost vertically with the first pinch seal portion down. A thermal insulating plate is provided in a boundary position between the light emitting tube portion and a portion to be pinch-sealed in an outer peripheral space of the quartz glass tube. Liquid nitrogen is jetted from a cooling nozzle provided obliquely below the light emitting tube portion toward the same, thereby cooling the light emitting tube portion. The portion to be pinch-sealed is heated with a burner, and pinch-sealed with a pincher immediately thereafter.

Method of manufacturing arc tube

An arc tube and method for forming an arc tube in which an electrode assembly including a tungsten electrode and a molybdenum foil are joined together in a partially overlapped state and pinch sealed into a pinch seal portion of the arc tube body to suppress leakage due to peeling of the molybdenum foil and prolong the life period of the arc tube. An overlapped length L of a tungsten electrode and a molybdenum foil is set to be 2D&lE;L &lE;0.8W with respect to the diameter D of the tungsten electrode and the width W of the molybdenum foil. In another embodiment, the distance L between the molybdenum foil and a discharge space is set to be B&lE;L &lE;0.8A with respect to the width A and the thickness B of a pinch seal portion.

Arc tube with pinch seal and dimensional relationship and method for forming the same

A discharge bulb including: an arc tube having a light emitting portion constructed in a manner that a light emitting substance is enclosed therein by pinch-sealing the arc tube, and discharge electrodes are oppositely arranged therein; and a shroud glass tube hermetically sealing and covering the arc tube, so as to form a space between the shroud glass tube and the arc tube. And a water content or pressure of gas enclosed in the sealed space is specified.

Discharge lamp and manufacturing method thereof

A method of manufacturing an arc tube for a discharge lamp unit, incorporating a primary pinch-sealing step for mounting an electrode assembly in an open end of a glass tube W with a chamber portion . The electrode assembly comprises an electrode rod , a connecting foil and a lead wire integrally connected in series. The electrode assembly is inserted into an open end of the glass tube W such that a leading end of the electrode rod projects into the chamber portion . A temporary pinch seal region L of the glass tube W is pinch-sealed such that a portion of the connecting foil that is connected to the lead wire is contacted by the glass tube W. A vacuum is maintained inside the glass tube and a main pinch seal region L of the glass tube is pinch-sealed such that a portion of the connecting foil connected to the electrode rod is contacted by the glass tube. When the main pinch seal region L of glass tube W is pinch-sealed, the negative pressure in the glass tube W is exerted on the softened sealed chamber portion owing to supplied heat as well as the pressure exerted from the pincher . Thus, the glass layer is pressed against the surface of the molybdenum foil so that hermetic contact is realized.

ARC tube for discharge lamp unit and method of manufacturing same

The amount of a metal halide to be enclosed in a generally ellipsoidal discharge space within a discharge vessel is set in the range 0.006-0.01 mg per unit volume (&mgr;l) of the discharge space . If the amount is less than 0.01 mg/&mgr;l, the deposit of metal halide on the inner surface of the discharge space in its lowest position midway between the narrow end portions thereof will not cause &ldquo;shunting&rdquo; of the arc between the electrodes A, B. As a result, the arc is effectively prevented from fizzling out after the metal halide lamp is switched on. To ensure that the metal halide lamp produces the intended luminous flux and color of light, the amount of the metal halide to be enclosed in the discharge space should not be lower than 0.006 mg/&mgr;l.

Metal Halide lamp having improved shunting characteristics

An arc tube provided with a central sealed chamber , in which light-emitting substances are enclosed, having a pair of electrode assemblies disposed opposite to each other. The electrode assemblies are sealed in pinch seal portions . The arc tube incorporates a residual-compressive-stress layer formed on a surface of the glass layer in each of the pinch seal portions that contacts the electrode rod included in each electrode assembly. The residual-compressive-stress layer has a length greater than or equal to 30% of the axial length of a glass layer region that only contacts the electrode rod and/or an angular range greater than or equal to 180&deg; in a circumferential direction of the electrode rod. Thermal stress (tensile stress) produced in the boundary between the glass layer and the electrode rods after the arc tube has been turned on is absorbed and dispersed by the residual-compressive-stress layer surrounding the electrode rods . Thus, any vertical crack that would result in the light-emitting substances leaking from the sealed chamber does not form in the glass layer of the pinch seal portions

Arc tube with residual-compressive-stress layer for discharge lamp unit and method of manufacturing same

Arc tube for discharge lamp device and method of manufacturing the same

The pinch-sealing for the first one of a pair of molybdenum foils is not performed by flowing inactive gas within a quartz glass tube like the prior art but performed in a manner that the lower end portion of the quartz glass tube is sealed, and then and a pinch seal estimation portion is squeezed by a pincher while air within the quartz glass tube is exhausted from the upper end portion thereof so that pressure within the quartz glass tube becomes in a negative pressure state of 100 torr or less and while heating the pinch seal estimation portion Accordingly, at the time of the squeezing, the inner wall surface of the pinch seal estimation portion thus heated is attracted to the molybdenum foil side thereby to form fine concave and convex portions on the interfaces between the molybdenum foil and the quartz glass tube so that the molybdenum foil and the quartz glass tube are placed in an engaged state and the contact area therebetween is increased.

Arc tube and fabricating method thereof

An electric discharge lamp apparatus which incorporates an arc tube,structured such that an enclosed glass bulb,of an arc tube body,is enclosed in an ultraviolet-ray shielding globe,and having a front end which is supported by a metal lead support,forwards extending from an insulating plug,provided with a focusing ring,and made of synthetic resin and which has a structure that a rear end of the globe,of the arc tube,is supported by a metal support member,secured to the insulating plug,wherein the metal support member,is constituted by a metal base plate,secured to the insulating plug,and forming a reference plane f,running parallel to the focusing ring,on the front surface of the insulating plug and a metal vertically-holding member,(a slide plate,and an arc-tube holding band,) integrally joined to the metal base plate,and arranged to vertically hold an electrically-discharge axis L of the held arc tube,with respect to reference plane f,of the metal base plate,so that the electrically-discharge axis L of the arc tube,is accurately brought to a predetermined required position with respect to the focusing ring

Electric discharge lamp apparatus

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

Electric discharge lamp apparatus with insulating plug

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.

Electric discharge lamp apparatus and insulating plug therefor having a particular front portion

A metallic halide lamp has an envelope of silica glass defining a discharge chamber with a pair of pinch seals extending in opposite directions therefrom. A pair of tungsten electrode stems are partly buried in the respective seals and electrically connected to a pair of molybdenum lead wires via a pair of molybdenum foils which are wholly embedded in the pinch seals. The molybdenum foils have a recrystallization grain size of not more than about 50 .mu.m.

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Shizuoka, Japan

Yoshitaka Ohshima