Abstract: A starting circuit for an electrodeless high intensity discharge lamp comprises a high efficiency power supply for providing a radio frequency signal to a starting probe disposed proximate the arc tube of the lamp. The power supply may comprise either a Class-D or Class-E power amplifier having an output resonant circuit tuned to a substantially higher frequency than the operating frequency of the signal provided to the excitation coil by the lamp ballast to ensure minimal interaction between the starting circuit and the ballast. The output resonant circuit includes an inductance coupled in series with a capacitance that preferably comprises the capacitance between the excitation coil and the starting probe. After initiating the arc discharge, the starting circuit is deactivated.

Abstract: A starting aid for an electrodeless high intensity discharge (HID) lamp comprises a spiral starting electrode which, at least during lamp starting, conforms to the shape of the arc tube so as to provide a relatively high capacitive starting current upon receipt of a radio frequency starting signal, resulting in a rapid transition from a glow discharge to a high intensity solenoidal discharge. At least one turn of the spiral starting electrode is preferably in contact with the portion of the arc tube nearest the arc discharge to be formed and is oriented so as to provide a capacitive starting current that flows in substantially the same location as the arc discharge to further ease lamp starting. In one embodiment, the spiral starting aid comprises first and second coil portions. The first coil portion conforms to the shape of the arc tube and has at least one turn disposed nearest the portion of the arc tube where the arc discharge is to be formed.

Abstract: A ballast for an electrodeless high intensity discharge lamp comprises a Class-D power amplifier including an integrated tuning capacitor network and heat sink. A series blocking/tuning capacitor and a parallel tuning capacitor are integrated by sharing a common capacitor plate. The metal plates of the parallel tuning capacitor also comprise heat sink planes to remove excess heat from the excitation coil of the lamp. Heat sink fins are affixed to the plates of the parallel capacitor. Efficiency is maximized by matching the impedance of the ballast load network.

Abstract: A package for a two-switching-device half bridge circuit comprises an insulating substrate having first, second and third external power terminals along with control terminals bonded to the substrate. The power terminals are configured to provide a straight-through-the package current path from the first external power terminal to the second or common external power terminal and from the second or common external power terminal to the third external power terminal. The control terminals are preferably Kelvin terminal pairs in order to minimize feedback from the power current paths to the control circuits. The power devices are preferably bonded to the first external power terminal and the second external power terminal, respectively, with their connections respectively to the second power terminal and third power terminal substantially identical in order to provide power current paths through the package having substantially identical electrical and thermal impedances.

Abstract: A lamp ballast configuration in which input power is conducted by one circuit board to the switching devices of a half bridge circuit whose output is conducted on a second circuit board with the two circuit boards mounted parallel and spaced apart disposes the device package which extends between the two circuit boards in an exposed position for direct contact to a heat sink. Drive transformers for the switching devices are preferably mounted between the circuit boards and shielded on four of their six sides by a combination of ground planes on the circuit boards and wide, flat ground conductors connecting the ground planes of the two circuit boards. A compact, high efficiency (>91%) RF system is obtained which is suitable for excitation of an electrodeless, high-intensity-discharge lamp.

Abstract: A driver circuit for a voltage-switching, high frequency Class-D power amplifier provides an input sinewave power signal and controls the transition time between switching the two active devices thereof, resulting in substantially lossless switching. The transition time is optimized by controlling the amplitude of the voltage signals at the inputs of the two active devices, depending on the output capacitance of the switching devices, the threshold voltage of the switching devices, the power output requirement, and the impedance of the resonant load network of the Class-D power amplifier.

Abstract: A power factor correction circuit employs a metal oxide varistor in series with a filter capacitor. The varistor provides a low-impedance path for pre-charging the filter capacitor, thus enabling the avoidance of high inrush current to circuit devices, while the filter capacitor energizes the circuit when the capacitor voltage exceeds the AC source voltage. The circuit is insensitive to normal line transients. One application is for use in a gas discharge lamp ballast.

Abstract: A high intensity discharge electrodeless lamp having a segmented excitation coil and capacitor configuration offers minimum light obstruction and RF losses while providing maximum impedance matching and heat transfer from the coil to a heat sink. The excitation coil includes at least two pairs of interconnected windings, each pair disposed concentrically in its own plane. The windings are clustered in a toroidal shape, the center of which is positioned to surround the arc envelope of a high intensity discharge lamp containing an ionizable gas activatable by RF energy. The coil windings are of large cross-sectional area and the capacitors have short leads, so as to minimize EMI and power losses and facilitate heat condition to heat sink means. The windings are configured to follow the contours of the magnetic field lines created by current flow through the total coil.

Abstract: All the magnetic functions required in a ballast for a fluorescent lamp are integrated in a single, standard magnetic core which provides isolation, voltage step-up, ballasting, power factor correction and cathode heat for multiple lamps operating multiple lamps in an isolated-series configuration. In a three-legged transformer core embodiment, the primary winding is continuously wound on all three legs, while secondary windings are included on two of the legs. Ballasting inductance is provided by winding the primary on the third leg. The number of primary turns N.sub.p necessary to avoid saturation of the transformer for any specific input voltage and core material, the number of primary windings N.sub.p1 on the secondary legs and the number of primary windings N.sub.p2 on the third leg are determined according to the equation 2N.sub.p1 =N.sub.p -N.sub.p2.