Toto Ltd.

Tetsuaki Bundo

Koichi Hayashi

Hirotaka Ishibashi

Hiroaki Nagai

Naohito Wajima

Susumu Narita

Koji Kita

Nobuyuki Yamada

In a discharge lamp sealing apparatus , luminescent substances are charged into an arc tube through an opening thereof, and an electrode member is then inserted into the arc tube through the opening 13 . A lower end of the arc tube is supported by a support jig in a state that a glass ring is placed around the circumference of the opening . The arc tube is set in an air-tight condition by a feeding conduit and inserted into a heating unit . The heating unit fuses the glass ring with heat of an infrared lamp and thereby seals the opening . During the sealing process, one end of the arc tube is supported by the support jig . The support jig is mainly made of a material having a greater thermal conductivity than that of the material of the arc tube , for example, a metal material like Al or Cu. This arrangement enables heat to be readily conducted from the arc tube to the support jig and accordingly prevents a temperature rise in the arc tube . This prevents the luminescent substances from being vaporized and released from the arc tube

Discharge lamp, discharge lamp sealing method, discharge lamp sealing device

Light-transmissive ceramics are disclosed composed of a plurality of oxides each having a negative standard Gibbs energy of formation (.DELTA.Gf.sup.0) with an absolute value greater than 1581.9 KJ/mol. The light-transmissive ceramics are produced by subjecting the oxides to hot isostatic pressing at a high temperature under a high pressure after they have been subjected to primary sintering. The light-transmissive ceramics of Al.sub.2 O.sub.3 /La.sub.2 O.sub.3 are of a composite structure with particles of La.sub.2 O.sub.3 being present between particles of Al.sub.2 O.sub.3, rather than Al.sub.2 O.sub.3 and La.sub.2 O.sub.3 forming a solid solution. In the composite structure, the particles of La.sub.2 O.sub.3 have sizes that are 1/3 to 1/30 of the particles of Al.sub.2 O.sub.3. Maximum size particles of Al.sub.2 O.sub.3 have a longer axis of 30 .mu.m or less and a shorter axis of 20 .mu.m or less, and maximum size particles of La.sub.2 O.sub.3 or the like have a longer axis of 10 .mu.m or less and a shorter axis of 5 .mu.m or less. Before an a molded ceramics body is fully fired, it may be processed by a chelating agent, and perhaps also with hydrofluoric acid, to remove impurities therefrom for improving characteristics of the light-transmissive ceramics.

Light-transmissive ceramics and method of manufacturing same

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Kitakyushu, Japan

Tetsuaki Bundo