Hitachi, Ltd.

Ikuya Nomoto

Kenji Kawabata

Ichiro Torii

The discharge lamp operating circuit comprises two series circuits, each including two switching devices, connected in parallel with the power supply, a series circuit, including a choke coil, a first capacitor, and a parallel circuit with a discharge lamp and a second capacitor, and connected between the middle points of the one and the other series circuit, reverse-direction rectifiers connected in parallel with the corresponding switching devices, said discharge lamp operating circuit turning on and off said discharge lamp by turning on and off the switching devices alternately. In this discharge lamp operating circuit, the timing of switching the switching devices is set from the closed condition to the open condition at a time when the current flowing through the switching devices is almost at zero level.

Discharge lamp operating circuit

A discharge lamp operating circuit includes at least a discharge lamp, a condenser and four switches. The condenser is charged and discharged through the discharge lamp by the turn-on and turn-off of the switches so that an AC current is caused to flow through the discharge lamp to operate the discharge lamp. A time required for the complete charging and discharging of the condenser is selected to be longer than a time scheduled for the charging and discharging of the condenser in one period. A switching frequency f.sub.0 at the time of heating of the discharge lamp and a switching frequency f at the time of operating of the discharge lamp has a relation of 2.ltoreq.f/f.sub.0 .ltoreq.10.

A compact fluorescent lamp with a screw base having a lamp with an inner tube, an outer case which is provided at one end of the lamp and includes an operating circuit section therein and has a screw base at one end of the outer case, and a molding compound having excellent insulation and good conduction of heat which is pressed and interposed into the gap between the operating circuit section and the outer case in order to transfer the heat generated in the operating circuit section to the outer case.

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Akigawa, Japan

Ikuya Nomoto