Abstract: An internal electrode (14) is formed on the inner wall surface of a tube-shaped light emitting body (12) along the longitudinal direction of the light emitting tube (12). An external electrode (15) is formed on the exterior surface of the light emitting tube (12) along the longitudinal direction of the light emitting tube (12). An electric discharge starts between the internal electrode (14) and the external electrode (15) by applying a high-frequency voltage therebetween. Only one tube wall of the light emitting tube (12) lies between the internal electrode (14) and the external electrode (15), and the internal electrode (14) and the external electrode (15) can be brought close to each other. The limitation of an electric current running between the internal electrode (14) and the external electrode (15) can be reduced, and a starting voltage or a discharge-maintaining voltage can be lowered. In addition, the internal electrode (14) can be easily processed with high accuracy.

Abstract: The present invention provides a high-voltage discharge lamp having an internal volume of 0.05 cc or less that is small yet maintains a desirable lifetime and a high luminous efficiency, a high-voltage discharge lamp device using the lamp, and a lighting apparatus using the lamp. The high-voltage discharge lamp comprises a ceramic discharge vessel that has a spherical, bulging section and a pair of small diameter cylindrical sections. The spherical, bulging section surrounds a discharge space. The small diameter cylindrical sections are connected to the ends of the spherical, bulging section. Electrode-integrated power-supplying conductors are used. Each conductor comprises a seal part and a halide-resistant part. The halide-resistant part having a proximal end connected to the distal end of the seal part. The distal end of the halide-resistant part projects into the spherical, bulging section of the translucent ceramic discharge vessel forming an electrode.

Abstract: A low-pressure mercury vapor-filled discharge lamp has a glass arc tube and a glass outer tube disposed coaxially with the arc tube forming a space therebetween. A gas is disposed in the space. The arc tube contains a gas and is coated with a phosphor. A first seal hermetically seals the inner tube. A second seal seals the inner tube to the outer tube. The inner tube further contains a pair of cathodes coupled to Dumet wires extending from the interior of the inner tube to the outside of the lamp structure. The pressure in the space is set at not more than 1 Pa, which is nearly high vacuum. The longer the radial dimension of the space, the greater the heat retaining capacity and the better the temperature characteristics which can be obtained. However, by setting the pressure of the space at 1 Pa or less, the optimum heat retaining capacity can be obtained while reducing the diameter of the low-pressure mercury vapor filled discharge lamp 1.