Abstract: An electronic ballast for high intensity gas discharge lamps where the wave form of the lamp current is square wave providing acoustic resonance and flickering free operation. The circuit, having high efficiency, operates in a wide temperature range providing ideal ballast curve and reliable ignition for the lamps. Furthermore, significant energy saving can be achieved by its externally controlled built in dimming capability.

Abstract: An electronic ballast for high intensity gas discharge lamps where the wave form of the lamp current is square wave providing acoustic resonance and flickering free operation. The circuit, having high efficiency, operates in a wide temperature range providing ideal ballast curve and reliable ignition for the lamps. Furthermore, significant energy saving can be achieved by its externally controlled built in dimming capability.

Abstract: The invention pertains to a switchmode power inverter, and particularly to a half-bridge inverter for asymmetrical load. More particularly, the invention pertains to high frequency electronic ballast for gas discharge devices, especially for high intensity discharge lamps, completed by an internal high voltage ignition circuit and transient current control protecting against the asymmetrical feature of high intensity discharge lamps at startup.

Abstract: The invention pertains to a switchmode power inverter, and particularly to a half-bridge inverter for asymmetrical load. More particularly, the invention pertains to high frequency electronic ballast for gas discharge devices, especially for high intensity discharge lamps, completed by an internal high voltage ignition circuit and transient current control protecting against the asymmetrical feature of high intensity discharge lamps at startup.

Abstract: The invention pertains to a switchmode power inverter, and particularly to a frequency controlled half-bridge inverter. More particularly, the invention pertains to high frequency ballast for gas discharge devices, especially for high intensity discharge lamps, completed by an internal high voltage ignition circuit and an external control apparatus for dimming.

Abstract: A low frequency square wave electronic ballast used for a gas discharge device includes a high power factor pre-regulator connected to a sinusoidal AC power supply and a power controlled DC current source connected to the pre-regulator. A low frequency square wave DC-to-AC inverter is connected to the DC current source and an ignitor circuit is connected to the inverter. A monitor circuit as well as a low power stabilized logic supply voltage source are also employed. The entire circuit is connected to a gas discharge device such that the instantaneous power of this device is constant and controlled providing an acoustic resonance free operation and an ideal ballast curve.

Abstract: The invention pertains to a switchmode DC to AC converter, and particularly to a master-slave half-bridge converter. The slave half-bridge power converter is controlled by a lower power self-oscillating half-bridge master converter. More particularly, the invention pertains to a high frequency ballast for gas discharge devices, especially, for high pressure sodium lamps, completed by a high voltage ignition apparatus. A pair of self-saturated electronically switched transformers controlled by a low power current source provide a power controlled and frequency modulated high frequency ballast for the gas discharge devices.

Abstract: The invention pertains to a switchmode DC-to-AC inverter, and particularly to a self-symmetrized and self-oscillating half-bridge inverter. More particularly, the invention pertains to a high frequency ballast for gas discharge devices, especially for high intensity discharge lamps, including power control, frequency modulation and high voltage ignition apparatus.

Abstract: A power factor correction circuit used to improve the ratio of real power to apparent power in an electric power distribution line containing a source of AC sinusoidal voltage and a load. The circuit includes a frequency and amplitude modulated boost converter forcing the input current to have the same wave shape as that of the input voltage.

Abstract: A switchmode DC to AC converter, and particularly a master-slave half-bridge converter. The slave half-bridge power converter is controlled by a lower power self-oscillating half-bridge master converter. More particularly, the invention pertains to a high frequency ballast for gas discharge devices, especially, for high pressure sodium lamps, completed by a high voltage ignition apparatus.

Abstract: A circuit system for igniting and lighting a high-pressure discharge lamp, particularly a sodium vapor lamp, comprising a pulse generator for generating signals of at least 1 kHz frequency being a high-frequency DC/AC converter connected to a direct current source and an ignition circuit coupled with the pulse generator including a high-pressure discharge lamp, a condenser connected in parallel to the high-pressure discharge lamp and an inductive member connected to the condenser and the high-pressure discharge lamp and forming a series member with the condenser the ignition circuit is provided with a transformer having a secondary winding connected in series with the inductive member for ensuring high reliability of igniting and for improving the conditions of lighting.

Abstract: A fuse-element for electric fuses is shaped as a metal strip with one or more zones of diminished cross-section.The temperature rise conditions of the fuse-element and of its zones of diminished cross-section can be established and evaluated in combination and--based on these data--a fuse-element can be designed the temperature distribution characteristics of which include different local peak values and the spots where such peak values develop can be set in a manner that the whole fuse-element consists of two parts as far as the temperature distribution is concerned, i.e. a first part where this distribution is in accordance with a steady state distribution (the highest current value still failing to cause any melting), and a second part where the temperature rise distribution determines the character of the melting process, this being the so-called transient distribution characteristic.

Abstract: A fuse-element for use in an electric network, includes a metal strip including at least one portion having a reduced cross-section, a shunt element of conductive material shunting the portion, bonding means conductively bonding the shunt element to the metal strip and being capable of being released at a temperature higher than a predetermined temperature, the shunt element defining a chamber facing towards the metal strip and being sealed by the bonding means between the metal strip and the shunt element, and a material disposed in the chamber having a boiling temperature below the predetermined temperature and capable of producing an internal gas pressure within the chamber sufficient to break the bond when the material is heated to a temperature higher than the boiling temperature.