Sansha Electric Manufacturing Company, Limited

Takashi Tsujii

Kenzo Danjo

Masataka Nishimura

Haruo Moriguchi

Hiroki Morimoto

An output of a rectifying circuit (), which rectifies commercial AC power, is supplied to an inverter () through a power factor correction circuit (). The output of the inverter () is voltage-transformed in a transformer (), rectified in a rectifying circuit () and is applied to a xenon lamp (). A secondary winding () of a transformer () of an igniter () is connected between the rectifying circuit () and the xenon lamp () in order to generate an arc in the xenon lamp (). A pulse generator provides a pulse for a short time period to a primary winding () of the transformer (). An auxiliary power supply () supplies arc-sustaining current prepared based on the commercial AC power to the junction of the rectifying circuit () and the secondary winding () of the transformer ().

Power supply apparatus for arc-generating load

A power supply apparatus for a light source includes an input-side rectifier ( ) which converts an input AC signal to a DC signal, and a high-frequency inverter ( ) which converts the DC signal to a high-frequency signal. An output-side rectifier ( ) converts the high-frequency signal to a DC output signal for application to the light source. Power detecting means ( ) detects the power supplied to the light source through the application of the DC output signal thereto, and develops a power representative signal. A control circuit ( ), a summer ( ) and an error amplifier ( ) cooperate to control the high-frequency inverter ( ) in accordance with the power representative signal in such a manner that power of a predetermined value can be supplied to the light source. An input current detector ( ) detects the input AC signal current value and develops an input current representative signal. When the input current representative signal is smaller than a predetermined input current reference value, a summer ( ) and an error amplifier ( ) cooperate to provide the summer ( ) with such a control signal as to maintain the input AC signal current value at a predetermined value.

Power supply apparatus for light source

A power supply apparatus useful for starting and driving a discharge lamp includes a DC-to-DC converter for converting a DC signal from a DC power supply to a second DC signal having a predetermined magnitude which is supplied to the lamp. A current detector develops a DC current representative signal representing DC current supplied to the lamp from the DC-to-DC converter. A combination of the current detector a DC voltage detector and a multiplier develops a DC power representative signal representing DC power supplied from the DC-to-DC converter to the lamp. An error amplifier develops a DC current error signal representing the difference between the DC current representative signal and a predetermined DC current reference signal. An error amplifier develops a DC power error signal representing the difference between the DC power representative signal and a predetermined power reference signal. For a predetermined time period following the start of operation of the power supply apparatus, a combination of a delay circuit a comparator and a clamping diode clamps the DC power error signal so that only the DC current error signal can be outputted. A driver unit controls the DC-to-DC converter in such a manner as to make the DC current error signal zero.

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Osaka, Japan

Takashi Tsujii