Hamamatsu-photonics K.k.

Nobuharu Harada

Syoji Ishihara

Yuji Shimazu

Keiji Suyama

Tatsuo Kurashima

Kouji Makino

In a light source, a heat sink is in contact with a side-on type discharge tube. The heat sink is in contact with a peripheral regionaround an exit windowof the discharge tube. The heat sink consists of a spring memberkept in direct contact with the peripheral region, and a radiating blockwhich connects the spring memberto a radiator box. Since materials made by sputtering or the like of electrodes in the discharge tubemostly attach to the peripheral regionof side wall, it is feasible to decrease the amount of materials attaching to the exit windowand, in turn, lengthen the lifetime of the discharge tube. Another light source may be constructed in structure in which the heat sink is in contact with a head-on type discharge tube or in structure in which light is outputted from a projecting portion.

Light source

A discharge tube is comprised of a glass bulb, a cathode, and an anode. Impregnating porous tungsten with barium makes the cathode tip portion. A clearance between the end face of a lead rod and the end face of the cathode tip portion is filled with a molybdenum-ruthenium brazing filler metal.

Electrode for discharge tube, and discharge tube using it

A discharge tube in which a cathode with a cathode tip portion being fixed to a lead rod and an anode opposed to the cathode tip portion are encapsulated in a discharge gas atmosphere to effect arc discharge, wherein the cathode tip portion comprises: a metal substrate of an impregnated type in which a porous, refractory metal is impregnated with an electron-emissive material or a sintered type in which a refractory metal containing an electron-emissive material is sintered; and a coating of a refractory metal covering a predetermined portion in a surface of the metal substrate and having a thickness of not less than 0.02 &mgr;m nor more than 5 &mgr;m, wherein the metal substrate has a cusp pointed toward the anode, and wherein a tip portion of the cusp of the metal substrate is exposed without being covered by the coating.

Discharge tube

In order to meet various requirements for discharge tubes for use as light sources, including easiness of production, stability of discharge, long lifetime, etc. without any contradiction between them, a discharge tube of the present invention involves an improvement in the discharge tube for use as a light source constructed to effect arc discharge in a discharge gas atmosphere between a cathode , having a cathode tip portion fixed to a lead rod , and an anode opposed thereto while keeping the cathode and anode enclosed in the gas. The cathode tip portion has a cusp pointed toward the anode and consists of a refractory metal substrate of an impregnated type or a sintered type containing an electron-emissive material, and a refractory metal coating covering the surface except at the tip portion of the cusp. At the tip portion of the cusp in the cathode tip portion, the metal substrate is exposed without being covered by the coating, or the coating is made so thin or porous as to substantially expose the metal substrate.

Growing community of inventors

Hamamatsu, Japan

Nobuharu Harada