Ushio Denki Kabushiki Kaisha

Akiko Uchino

Tomoyoshi Arimoto

Yukio Yasuda

Tetsuya Kitagawa

Shunichi Morimoto

Disclosed herein is a short arc discharge lamp which has a cathode electrode structure formed by solid-phase bonding a tip part made of thoriated tungsten to a body part made of tungsten. According to the present invention, the bonding strength between the body part and the tip part is increased to the same level as the mechanical strength of tungsten, thus preventing a breakage from being caused on a junction interface. For this, on a section of the cathode electrode taken along a line perpendicular to the junction interface, in an arbitrary portion of 500 &#x3bc;m or more in length along the junction interface, when a length of the arbitrary portion along the junction interface is set to L, and a sum of lengths of tungsten crystal grains, along the junction interface, that are present through the junction interface is set to L, (L/L0)&#x2267;0.16 is satisfied.

Short arc discharge lamp

A xenon short arc lamp for a digital projector, includes an anode, a cathode having a cathode main body that is made of tungsten containing electron emissive material, and an arc tube made of silica glass, wherein a supply source of carbon is formed on a metal portion in the arc tube except a tip area of the cathode, and the carbon is supplied to the tip of the cathode through a gaseous phase during lamp lighting, so that a surface layer of the cathode is melt.

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Himeji, Japan

Akiko Uchino