Matsushita Electric Works, Ltd.

Hiroichi Shinbori

Tsutomu Shiomi

Toshiaki Nakamura

Yutaka Iwahori

Shinji Hizuma

Takeshi Kamoi

Naoki Komatsu

Takeshi Goriki

Yiyoung Sun

Haruo Nagase

A discharge lamp lighting device which comprises a D.C. power supply, a load resonance circuit including an inductor, a capacitor and a discharge lamp; a polarity inverting circuit including at least a series circuit of first and second switching elements connected in parallel to the D.C. power supply for converting a D.C. power received from the D.C. power supply into an A.C. power to supply it to the load resonance circuit; and a control circuit for turning ON and OFF the switching elements alternately at a high frequency to alternately generate a first period during which an ON duration of the second switching element is longer than that of the first switching element and a second period during which the ON duration of the second switching element is shorter than that of the first switching element, to thereby apply a rectangular-shaped low frequency voltage to the discharge lamp. The control circuit superimposes a D.C. component in an output of the polarity inverting circuit upon a resonance pulse signal from the load resonance circuit to continuously change a switching frequency of the switching elements for the predetermined time from the start time point of one of the first and second periods, and supplies to the discharge lamp a first energy necessary for starting and lighting the discharge lamp with a high pulse voltage obtained through LC resonance and also for smoothly shifting the lamp to an arc discharge state.

Discharge lamp lighting device of high startability with high pulse voltage

Power source device including a plurality of switching circuit for power

A power device includes at least two power conversion circuits respectively having at least one of switching elements, at least one of which switching elements in these conversion circuits being used in common as an element constituting the at least two different power conversion circuits, a control device providing at least a period in which at least one of currents flowing from at least one of the different power conversion circuits to the commonly used switching element has a polarity inverse to at least the other one of the currents flowing from at least the other one of the power conversion circuits, so as to cancel each other, and a unit for detecting the state of the respective conversion circuits. The operation of the switching elements is thereby made modifiable in accordance with a lowering in the resistance of a load of the device, and the withstand voltage of the elements can be prevented effectively from rising even upon any fluctuation in the load.

Power device with commonly used switching elements

A power source device is so arranged that one of switching elements forming a plurality of power conversion switching circuits which is used in common during each switching cycle is made to have a switching period in which mainly a current is taken up from a power source of first one of the switching circuits, the switching period being varied in a zone in which an input voltage is higher than a predetermined voltage in a cycle of input voltage waveform. Any distortion of input current waveform occurring around lower voltage period of commercial AC source is thereby reduced, in the power source device wherein the power conversion switching circuits employ commonly the switching elements.

Power source device

A power supply apparatus in which a series circuit of first and second switching elements not blocking their reverse-directional currents is connected in parallel to a series circuit of a D.C. power source and a capacitor, a primary winding of a transformer is connected between a junction point of the D.C. power source and capacitor and a junction point of the switching elements, a secondary winding of the transformer is connected to a load circuit, and a controller is provided for controlling ON and OFF operation of the switching elements to cause a switching frequency of the switching elements to be set higher than a resonance frequency of the capacitor and an inductance of the transformer and to cause a voltage across the capacitor to increase.

Power supply apparatus

An inverter device made detectable at a high speed and highly precisely a load voltage of all waves in one cycle, with an arrangement including a voltage detecting means having a capacitor and connected to a load which is connected through a switching means to a DC power source, means connected to the voltage detecting means for charging and discharging the capacitor, and means for maintaining, in a predetermined period in which a transient voltage upon every inversion of load voltage is generated, a capacitor voltage immediately before the predetermined period.

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Kadoma, Japan

Hiroichi Shinbori