Abstract: A discharge lamp ballast having a starting circuit including a second inductor connected between a first end of a discharge lamp and the positive voltage side of a first capacitor; a second capacitor forming a resonance circuit together with the second inductor; a second switching element connected between the positive terminal of a DC power source and the second end of the lamp; a third switching element connected between the second end of the lamp and the negative voltage side of the first capacitor; and a starting controller that controls both switching elements. The starting controller alternately turns both switching elements on and off so as to contribute resonance voltage of the resonance circuit for starting of the lamp in case of the starting mode.

Abstract: In a chopper circuit, output power is controllable with a direct current power source as a power source, and a smoothing capacitor is connected between output terminals of the chopper circuit. A polarity inversion circuit applies an alternating voltage to a high pressure discharge lamp with a voltage across the smoothing capacitor as a power source. The output power of the chopper circuit and an inversion frequency of the polarity inversion circuit are controlled by a control circuit based upon a terminal voltage of the smoothing capacitor, which is detected by a voltage detecting circuit. In the control circuit, a switch voltage is set for defining a range of voltages detected by the voltage detecting circuit, and the inversion frequency is changed in plural stages according to the magnitude relation between the detected voltage and the switch voltage.

Abstract: A discharge lamp ballast. Its starting means comprises a second inductor connected between a first end of a discharge lamp and the positive voltage side of a first capacitor; a second capacitor forming a resonance circuit together with the second inductor; a second switching element connected between the positive terminal of a DC power source and the second end of the lamp; a third switching element connected between the second end of the lamp and the negative voltage side of the first capacitor; and a starting control means that controls both switching elements. The starting control means alternately turns both switching elements on and off so as to contribute resonance voltage of the resonance circuit for starting of the lamp in case of the starting mode. According to the invention, noise from the starting means can be reduced.

Abstract: In a chopper circuit, output power is controllable with a direct current power source as a power source, and a smoothing capacitor is connected between output terminals of the chopper circuit. A polarity inversion circuit applies an alternating voltage to a high pressure discharge lamp with a voltage across the smoothing capacitor as a power source. The output power of the chopper circuit and an inversion frequency of the polarity inversion circuit are controlled by a control circuit based upon a terminal voltage of the smoothing capacitor, which is detected by a voltage detecting circuit. In the control circuit, a switch voltage is set for defining a range of voltages detected by the voltage detecting circuit, and the inversion frequency is changed in plural stages according to the magnitude relation between the detected voltage and the switch voltage.

Abstract: A high intensity discharge (HID) lamp driving circuit. The HID lamp driving circuit includes a first pair of switching devices connected to a high frequency resonant filter, and a second pair of switching devices connected to a ripple reducing filter. A HID lamp is connected between the first pair of switching devices and second pair of switching devices, with a dc power supply being connected to the first pair of switching devices and the second pair of switching devices. The first pair of switching devices and the second pair of switching devices are connected to a common ground with the dc power supply. The lamp driving circuit operates in a half bridge topology during a start-up operation mode of the lamp, and operates in a full-bridge topology during a steady-state operation mode of the lamp. The HID lamp driving circuit is operated in an active zero current switching scheme.

Abstract: A discharge lamp driving circuit includes DC voltage input connections, lamp driving connections, bridge circuitry, and control circuitry. The bridge circuitry is connected to the DC voltage input connections and to the lamp driving connections and includes circuit elements which in one mode of operation deliver a higher frequency AC voltage to the lamp driving connections and in another mode of operation deliver a lower frequency AC voltage to the lamp driving connections. The control circuitry is connected to control the bridge circuitry selectively as either a half-bridge to deliver the higher frequency AC voltage to the lamp driving connections during starting or a full-bridge to deliver only the lower frequency AC operating voltage to the lamp while the lamp is operating normally after starting. A low frequency driver and a high frequency driver are connected to drive the bridge circuitry.

Abstract: A device for operating a high pressure gas discharge lamp with an electronic ballast having a lamp power factor of substantially 1.0. The device utilizes a lamp equi-luminescence performance curve X which is obtained for the lamp to give a lamp voltage and a lamp wattage that can vary along the curve X while keeping an arc luminescence of an arc developing between electrodes of the lamp at substantially constant level. The arc luminescence is defined as a maximum luminescence of the arc having varying luminescence along the length of the arc. The constant level determined to be the luminescence that the lamp gives at the rated lamp voltage. The curve X is analyzed to determine a specific lamp voltage Va at which curve X gives a maximum lamp wattage Wa. The lamp is operated in accordance with a first load characteristic for controlling to increase the lamp wattage substantially along the lamp performance curve X until the lamp voltage increases to the specific lamp voltage Va.

Abstract: A circuit for operating a discharge lamp at a low frequency AC voltage while repetitively interrupting at a high frequency the voltage component to be applied to the lamp. The circuit includes at least one switching transistor for repetitively interrupting the voltage to be applied to the lamp at the high frequency, for example, 40 KHz so as to allow the use of a light and less bulky inductor as the current limiting conductor to be connected in series with the lamp. A bridge inverter is provided to have at least one pair of switching transistors for alternately reversing a DC voltage to apply the resulting AC voltage to the lamp at the low frequency, for example, 100 Hz low enough to stably operate the lamp without suffering from acoustic resonance. The high frequency component is bypassed through a bypass capacitor connected in parallel with the lamp.