Matsushita Electric Industrial Co., Ltd.

Atsuo Waki

Koji Miyazaki

Shigeru Horii

Masataka Ozawa

Takayuki Kamitani

Takeshi Saito

Kazuhiko Ito

Masayoshi Gyoten

Nobuhisa Yoshikawa

Kazutaka Koyama

The present invention relates to an inverter driven lamp arrangement. The arrangement provides for the sensing of both lamp voltage and current. The arrangement also provides for a large current during times of low voltage and a small current during times of high voltage. The sensing of lamp current is done by a current detector that is connected to a resonance circuit whose output is applied in signal form to a lamp start control circuit. The resonant circuit is a series connected resonant circuit composed of a choke coil and a first capacitor. This series connected arrangement is further connected in series with a second non-resonant capacitor. Also the arrangement includes circuitry to gradually reduce the frequency of the inverter just after the lamp starts.

An inverter driven lamp arrangement having a current detection circuitry

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

When a discharge lamp is started, high voltage pulses which superpose the voltage due to LC resonance of a resonance circuit are supplied to the discharge lamp, and breakdown occurs in the discharge lamp. The pulse energy needed for the high voltage pulses is small and the output power of the resonance circuit can be decreased. After the breakdown, the energy needed for the transfer from glow discharge to arc discharge is supplied by the resonance, and the high voltage pulses used to supply the starting energy are allowed to be stopped. Thus, the starting and restriking of a discharge lamp is sure, and the starting circuit for a discharge lamp can be made more compact.

Discharge lamp starting circuit

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Osaka, Japan

Atsuo Waki