Matsushita Electric Industrial Co., Ltd.

Kazutaka Koyama

Shigeru Horii

Masataka Ozawa

Nobuhisa Yoshikawa

Kazuhiko Ito

Takayuki Kamitani

Makoto Horiuchi

Takeshi Saito

Koji Miyazaki

Masayoshi Gyoten

Takashi Katsura

Yoshiro Ogata

Atsuo Waki

A high pressure discharge lamp is disclosed. The high pressure discharge lamp includes: a discharge tube which is filled with gas; a first electrode having a first end, the first electrode being provided in the discharge tube; and a second electrode having a second end which is positioned away from the first end by a certain distance, the second electrode being provided in the discharge tube. In the high pressure discharge lamp, arc discharge is induced by a voltage applied between the first end of the first electrode and the second end of the second electrode. The high pressure discharge lamp further includes a convection regulating member which is electrically insulating and provided in the discharge tube. The convection regulating member suppresses the deformation of the arc discharge caused by the convection of the gas in the discharge tube.

High pressure discharge lamp having improved convection regulating means

In a discharge-lamp lighting apparatus for lighting a discharge lamp such as a metal halide lamp, there is provided a lighting control circuit which controls its output in a starting time of the discharge lamp in response to at least a length of the last off-time and an on-time after the start of discharging; and a power supplied to the discharge lamp is controlled in accordance with this output of the lighting control circuit.

Apparatus for controlling the power to a discharge-lamp

A high-pressure sodium lamp is connected to a d.c. power supply through a ballast, to operate it with a current containing a d.c. component. The relation between the ratio l/d of the inter-electrode distance l (mm) to the inner diameter d (mm) of the arc tube of the high-pressure sodium lamp and the sodium vapor pressure P.sub.Na (kPa) in the arc tube is maintained at P.sub.Na .gtoreq.6.0 (l/d-5.8), thus making it possible to operate the high-pressure sodium lamp with a current containing a d.c. component without causing a significant color separation which otherwise might be the result of cataphoresis.

Discharge lamp operation apparatus

A high pressure discharge lamp apparatus comprises:

High pressure discharge lamp apparatus

In a high pressure discharge lamp apparatus comprising a discharge tube and a current limiting device connected in series, an over-current protecting semiconductor switching device such as a triac (TC) is further connected in series to said discharge tube,

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Nishinomiya, Japan

Kazutaka Koyama