Toshiba Lighting & Technology Corporation

Akira Itoh

Kazuyoshi Okamura

Kazuiki Uchida

Hisashi Honda

Seiji Ashida

Shigehisa Kawatsuru

Kiyoshi Saita

Ariyoshi Ishizaki

Tatsuo Otabe

Hiroki Sasaki

Shinji Inukai

Yasuki Mori

Katsusuke Uchino

Akihiro Yonezawa

Kazuo Takita

Makoto Nishizawa

Kazuhiko Yoshikawa

Takayuki Aoki

Kimihito Sato

Hirochika Shiohama

Mitsuho Kotabe

A high-pressure discharge lamp which includes a light-transmitting air-tight discharge container, an electrode formed of tungsten as a main component and fixedly sealed in the discharge container, and a discharge medium containing a halide of a light emitting metal and sealed in the discharge container. The surface of the electrode is defined as follows. That is, the average value of center line average roughness Ra of the surface, is set to 0.3 &mgr;m or less, or the average value of the center line average roughness Rz of the surface of the electrode, is set to 1.0 &mgr;m or less, or the average value of the surface area increasing rate of the surface of the electrode is set to 1.0% or less.

High-pressure discharge lamp

High-pressure discharge lamp including a limited amount of carbon remaining on an electrode surface

In a discharge lamp having a discharge medium sealed in a discharge tube assembly including electrodes for producing a discharge, a nitride layer is formed on a surface of an envelope tube of the discharge tube assembly. The nitride layer is formed by substituting an oxygen component of an oxide constituting the tube wall of the envelope tube with nitrogen, and exhibits a continuous and smooth reduction in nitride content in the direction of depth. This chemically stable nitride layer prevents a reaction between the discharge medium and the tube wall material, and removal or injection of the discharge medium. In addition, since the nitride layer also exhibits a continuous change in thermal expansion coefficient in the direction of depth, the thermal stress is reduced, and cracking, peeling, removal, and the like do not occur.

Nitride layer for discharge lamps

The invention provides a high-pressure discharge lamp incorporating an outer envelope storing a pair of electric terminals a plurality of arc tubes which are respectively stored in this outer envelope and electrically connected in parallel, and a plurality of ignition aids available for assisting operating of these arc tubes, where these ignition aids are provided for each of these arc tubes and contain potentials different from each other. In addition, the invention also provides a lighting system for operating the high-pressure discharge lamp. The lighting system comprises the first and second power supply lines which respectively provides mutual connection between a pair of terminals of the high-pressure discharge lamp, a ballast which is at least provided for either of the first and second power supply lines, a power switch which is provided for either the first or the second power supply line, a pulse generating means which generates either the positive or the negative ignition pulses to be superimposed on AC power voltage output from an AC power supply source, and a control circuit which alters polarity of the ignition pulses output from the pulse generator.

High-pressure discharge lamp and lighting method

Sodium lamp

The invention provides a ceramic electric-discharge lamp having a pinch-sealer which is set to an end of an outer envelope and covered by a base having a pair of base pins projecting themselves into the base. The outer envelope is in vacuum, in which an arc tube composed of a square U-shaped tube is installed. Apertures of both ends of the square U-shaped illuminant are closed by ceramic discs each containing an electrode. Linear illuminant is formed in such regions where the radius of curvature of the square U-shaped arc tube greatly varies, in other words, between the curved portions.

Ceramic electric-discharge lamp incorporating arc tube having at least

Growing community of inventors

Yokohama, Japan

Akira Itoh