Abstract: An electronic ballast for a discharge lamp is capable of dimming the lamp over a wide range, yet assuring to operate the lamp efficiently with a minimum lamp power variation in compensation for a possible lamp characteristic variation. The ballast provides an unique voltage-wattage output characteristic which varies with a varying dimming ratio for reducing the lamp power as the dimming ratio decreases. The output characteristic is designed to follow a true lamp characteristic that the lamp voltage will decrease as the lamp power is reduced to a certain level. With this result, it is possible to give a wide voltage range within which the lamp power being supplied to the lamp is kept substantially constant irrespective of the lamp characteristic variation, thereby assuring to reduce the lamp power exactly as intended by the dimming ratio even in the presence of the lamp characteristic variation.

Abstract: An electronic ballast for a discharge lamp is capable of dimming the lamp over a wide range, yet minimizing a color temperature deviation. The ballast includes a power converter which converts an input DC voltage into a lamp power for driving the lamp, and a dimmer providing a dimmer command of a varying dimming ratio in order to reduce the lamp power to a greater extent as the dimming ratio decreases. A controller controls the power converter to supply a high frequency AC current to the lamp in response to the dimming ratio decreasing to a predetermined level, and to reduce an RMS value of the high frequency AC current as the dimming ratio decreases past the predetermined level.

Abstract: An electronic ballast for a high-pressure discharge lamp includes a power converter and a controller. In the power converter, the input DC voltage is converted into a ballast output power for lighting an HID lamp and applied to the HID lamp. The controller has a function to control the power converter and change the ballast output power. The ballast has power modification means. The lamp power modification means detects a lamp output parameter indicated after the HID lamp starts discharge, identifies a nominal lamp power of the HID lamp according to the output parameter, and gives an identification signal indicating the identified nominal lamp power. In response to this identification signal, the power converter outputs a ballast output power matched with the nominal lamp power identified by the controller.

Abstract: 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.

Abstract: A pulse generator for a stable output pulse voltage obtains a high voltage pulse with a charge accumulated in a capacitor and discharged at a discharge gap made ON, wherein a pulse energy source and a trigger source for conduction of the discharge gap are separately provided, so that the discharge gap will be conducted by a boosting action of the trigger source when a predetermined value is reached by a voltage of the pulse energy source.

Abstract: 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.

Abstract: A luminaire includes a lamp connected at one electrode to an ordinary current loop and at the other electrode to the other current loop which is branched into more than two which are extending along two opposite sides of the lamp. Magnetic fields produced thus in the branched loops act to cancel each other, and any noise occurring due to generation of the magnetic field can be remarkably reduced.

Abstract: A lighting device for a high-pressure discharge lamp includes an inverter circuit for converting a DC voltage into an AC voltage using a pair of switching elements. The switching elements have a switching frequency for starting the high-pressure discharge lamp that is higher than a resonance frequency of a series resonance circuit connected in parallel with the discharge lamp. However, in a lighted state of the discharge lamp, the switching frequency is lower than the resonance frequency of the resonance circuit and is within a frequency range where acoustic resonance does not occur. The lighted state of the high-pressure discharge lamp is maintained by a voltage across a capacitor in the series resonance circuit.