Abstract: An electronic ballast for a high intensity discharge lamp (HID) includes a power converters, a controller, and a lamp power switch. In the power converter, an input DC voltage is converted into a ballast output power for lighting the HID lamp. The controller has a function to control the power converter and change the ballast output power. The lamp power switch detects a lamp output parameter indicated after the HID lamp starts discharge, identifies a lamp power of the HID lamp according to the lamp output parameter, and gives an identification signal indicating the lamp power. In response to this identification signal, the power converter outputs the ballast output power which matches with the lamp power identified.

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 ballast includes a voltage converter providing a DC power from a DC source voltage. The converter includes a switching element and an energy storing element having an inductance. The switching element is controlled to operate for repetitively switching the DC source voltage in order to store energy into the energy storing element. A power converter is included in the ballast to receive the energy and convert it into an operating power for driving the discharge lamp. A controller provides a command value and turns on and off the switching element for variable periods, respectively in accordance with the command value for generating a necessary power to the lamp. The controller gives a variable OFF-period and a variable ON-period to the switching element. The controller gives a minimum OFF-end limit and a forced maximum OFF-end limit for terminating the OFF-period, and also gives a minimum ON-end limit and a forced maximum ON-end limit for terminating the variable ON-period.

Abstract: A power source device restricts any increase in a switching current to switching elements commonly used in two such different power source circuits as chopper and inverter circuits, while maintaining control independence of these circuits, by setting a period in which among currents flowing to the commonly used switching elements, the current flowing at least from one of the power source circuits has a polarity inverse to that of the current from at least the other power source circuit, to be in mutually cancelling directions.

Abstract: 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.

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: An electric power source device includes a power converting circuit and a load circuit (LD) for receiving an output from the power converting circuit. The power converting circuit includes a rectifier element (DB) for rectifying an input from an alternating current source (AC), a smoothing capacitor (Ce) for smoothing an output from the rectifier element (DB) with a direct current, and switching elements (Q1, Q2) for generating high frequency voltage and current in response to receipt of a voltage of the smoothing capacitor (Ce).

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: 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.