Abstract: In a power-line-operated electronic ballast, an inverter converts a DC voltage to a high frequency current-limited operating voltage for a fluorescent lamp. The DC voltage is obtained, at least in part, by forward conversion of full-wave-rectified unfiltered power line voltage; which forward conversion is accomplished by high frequency switching of an energy-storing inductor, the switching being done by the very same inverter that provides the high frequency lamp operating voltage. As an overall result, power is drawn from the power line with a power factor higher than 98% and with a total harmonic distortion well under 20%.

Abstract: A self-oscillating half-bridge inverter is powered from a DC voltage source and has a series-turned high-Q LC circuit connected across its output. A pair of fluorescent lamps is normally series-connected across the tank capacitor of the LC circuit. Whenever the lamp load is not so connected, the magnitude of the high-frequency current flowing through the LC circuit would tend to increase to destructively high levels. To prevent this from taking place, a negative feedback control circuit manifestly limits the magnitude of the high frequency current by reducing the forward conduction duty-cycle of each of the two bridge transistors whenever the peak current magnitude exceeds a pre-determined level. In particular, during normally loaded operation, each of the inverter's two transistors operate with a nearly 50% forward conduction duty-cycle. However, whenever the magnitude of the high frequency current exceeds a pre-determined level, the control circuit acts to shorten the forward conduction duty-cycle.

Abstract: A ballasting system for powering an array of flourescent lamp assemblies, as in a sun tanning apparatus, comprises an electronic frequency converter adapted to convert ordinary 60 Hz power line voltage into two non-current-limited high frequency outputs: a first output of 400 Volt/30 kHz sinusoidal voltage provided between a first pair of distribution conductors, and a second output of 50 Volt/30 kHz sinusoidal voltage provided between a second pair of distribution conductors. Each lamp assembly comprises two mutually parallel-disposed series-connected fluorescent lamps. The 50 Volt/30 kHz voltage is provided to the one end of this assembly and is used by way of an isolation transformer means to provide cathode heating power for the two lamp cathodes located near that end.

Abstract: A lighting arrangement comprises;(i) a plurality of pairs of mutually parallel-oriented fluorescent lamps, each pair of lamps adapted to be powered from 30 kHz/240 Volt by way of a high-Q series-resonant L-C ballasting circuit;(ii) a relatively low-power frequency converter connected with the power line and operable to provide power for heating the cathodes in these fluorescent lamps, thereby conditioning the lamps for easy starting;(iii) a relatively high-power frequency converter also connected with a power line and operable to provide the 30 kHz/240 Volt required for operating the plurality of pairs of fluorescent lamps by way of the high-Q series-resonant L-C ballasting circuit; and(iv) delay means operable to prevent the 30 kHz/240 Volt provided by the high-power frequence converter from being applied to the fluorescent lamps until after power has been applied to heat the lamp cathodes for at least one second.

Abstract: In a microwave oven, a magnetron is powered by way of a self-oscillating flyback converter circuit, which operates at a conversion frequency controllable over a range of frequencies up to about 35 kHz. The converter circuit is powered from a DC voltage derived from full-wave-rectification and filtering of ordinary 120 Volt/60 Hz power line voltage. The output of the converter is applied to the magnetron by way of a flyback transformer.In one preferred configuration, the output fromthe flyback transformer is applied dirrectly to the magnetron--without the use of an intermediary rectifier. As a result, current to the magnetron is provided inthe form of triangularly-shaped pulses with a duty-cycle of about 60% and with a crest-factor of less than 3.5.In a second preferred configuration, the output from the flyback transformer is rectified and filtered by a capacitor-inductor combination, with the result of providing a nearly constant-magnitude current to the magnetron.

Abstract: A fluorescent lamp is connected in parallel with a resonant L-C circuit powered by a series-applied high frequency voltage from a self-oscillating inverter power supply. The frequency of the series-applied voltage is about 33 kHz during the brief initial period before the lamp ignites, but falls to about 30 kHz after the lamp has ignited. As a result, the detuning taking place in the L-C resonant circuit due to changing parallel-loading is compensated-for by correspondingly changing the frequency of the series-applied voltage. This detuning effect is particularly pronounced in situations where there is a large magnitude-ratio between the lamp's ignition voltage and its operating voltage.

Abstract: A full-bridge inverter ballast for a fluorescent lamp comprises two pairs of switching transistors and is conditionally operable to self-oscillate in either of two modes: a first mode wherein one of the two pairs of switching transistors self-oscillates in manner of a half-bridge inverter and powers the thermionic cathodes of the fluorescent lamp, and a second mode wherein both pairs of transistors self-oscillate in manner of a full-bridge inverter and then powers the main gas discharge of the fluorescent lamp. The first mode gets initiated immediately upon applying power to the ballast, but the second mode does not get initiated until about 1.5 seconds after the initiation of the first mode. The way, the cathodes will have become fully thermionic prior to applying main power to the fluorescent lamp.

Abstract: A resonant L-C circuit is series-excited from an AC voltage source and intended to be parallel-loaded with a load that, for some reason or another, may be disconnected or otherwise inoperative. For efficiency reasons, the unloaded circuit Q-factor may be about 50 times higher than the loaded Q-factor; which implies that, if the load were to become inoperative, the power drawn by the L-C circuit from the source, and the voltage/current magnitudes developed in the L-C circuit, would be 50 times larger than when the load is operative. To prevent unnecessary power drain and/or to avoid damage to source and/or circuit components, which damage may occur even if the L-C circuit is left unloaded for but a very brief period, a circuit protector is provided.

Abstract: A self-contained electronic air register controller can easily be mounted directly onto the outside of an air register. When so mounted, the controller engages the register's actuating lever and permits automatic opening and closing of the air register by way of simple programming instructions and/or by way of a temperature sensor. The controller comprises a small battery, a miniature electric motor with a gear/linkage mechanism operable to engage with and to move the register's actuating lever between its OPEN and SHUT positions, and a quartz-clock-based programming means.

Abstract: A self-oscillating half-bridge inverter is powered from a power-line-operated DC voltage source and has a series-tuned high-Q LC circuit connected across its output. A pair of fluorescent lamps is series-connected across the tank capacitor of the LC circuit. An EMI filter is positioned between the inverter and the power line, thereby to minimize electro-magnetic interference. This same EMI filter also acts to produce a control signal in case a ground fault current were to occur; which control signal is used for preventing the magnitude of the ground-fault current from exceeding acceptable limits.

Abstract: A self-oscillating inverter-type fluorescent lamp ballast has two modes of operation: (a) a first mode in which the inversion frequency is about 70 kHz and is resonant with a first tuned circuit by which power is supplied to the cathodes of the fluorescent lamp; and (b) a second mode in which the inversion frequency is about 30 kHz and is resonant with a second tuned circuit by which main lamp power is supplied. When the ballast is initially powered-up, it starts operation in its first mode, thereby providing cathode heating power without yet providing main lamp power. About one second later, after the cathodes have reached full incandescence, the inverter automatically changes into its second mode, thereby providing main lamp power while at the same time removing cathode heating power. If for some reason the lamp were not to ignite within about 10 milli-seconds, the inverter reverts back into its first mode; thereafter cycling between its two modes until the lamp does ignite.

Abstract: In a power-line-operated inverter-type fluorescent lamp ballast with a high-Q parallel-loaded resonant L-C circuit series-connected across the inverter's output, subject invention provides for means to prevent the destructive overload that may occur during the lamp starting period or if the lamp is removed or somehow fails to operate. In this ballast, the unfiltered pulsed DC output of a full-wave power-line-supplied rectifier means is applied to a pair of inverters: an auxiliary inverter for pre-conditioning the fluorescent lamp, and a main inverter for powering the lamp. The auxiliary inverter starts operating immediately upon application of power from the power line, and therefore immediately starts the process of pre-conditioning. The main inverter, however, is not started until after the lamp has completed its conditioning, at which time the lamp will adequately load the series-resonant L-C circuit and thereby prevent destructive overload.

Abstract: An electronic ballast provides a high-frequency current-limited voltage between a first socket terminal and a second socket terminal. These socket terminals are adapted to receive and hold a rapid-start fluorescent lamp. The first terminal has a relatively low-magnitude potential with respect to ground; the second terminal has a relatively high-magnitude potential with respect to ground. A person coming in direct or indirect contact with the second terminal is apt to receive a hazardous electric shock. A self-oscillating electronic inverter is operable to provide the high-frequency voltage. To provide an output, this inverter has to be triggered into oscillation. However, if no current flows from the first terminal, the inverter will automatically become disabled with 25 milli-seconds; whereafter it will not be re-triggered for about 1.5 seconds.

Abstract: A full-bridge transistor inverter is connected at its DC supply-side with an energy-storing capacitor. The inverter's output terminals are connected in series between a source of AC voltage and a load; which load may be an electric motor, a fluorescent lighting system, etc. By controllably switching the transistors of the inverter ON and OFF in synchronism with the frequency of the AC voltage, effective control of the flow of power between the AC source and the load is achieved. DC voltage on the energy-storing capacitor is obtained from the AC source by way of the timing of the switching action of the inverter.Hence, in contrast with the ordinary situation where an inverter is supplied with net power from its source of DC voltage and where this net power is then supplied to a load connected with the inverter's output, the present invention relates to a situation where no net power is supplied to the inverter from its source of DC voltage and where no net power is supplied from the inverter's output.

Abstract: In an inverter-type power supply, a self-oscillating full-bridge inverter is powered by unfiltered full-wave-rectified 120 Volt/60 Hz power line voltage and controllably triggered into oscillation each half-cycle of the power line voltage by way of simultaneously triggering two of the bridge's four transistors into conduction simultaneously. This is accomplished by way of discharging a charged-up capacitor by way of a Diac through a special trigger winding on each of two saturable current feedback transformers; each of which controls a pair of the bridge transistors.

Abstract: A ballasting system for powering an array of multiple parallel-oriented fluorescent lamps in a sun tanning apparatus comprises and an electronic frequency converter adapted to convert ordinary 60 Hz power line voltage into a 350 Volt/30 Hz sinusoidal voltage provided between a pair of bus conductors and suitable for directly powering each fluorescent lamp by way of a simple capacitive or inductive current-limiting reactance means. The fluorescent lamp cathodes are heated by way of individual transformers, with one transformer for each pair of lamp cathodes. Only two pairs of distribution conductors are required for powering the complete array of mutually parallel-disposed fluorescent lamp pairs regardless of the number of lamps involved, with one pair running along the one side of the array, and the other pair running along the other side of the array. Of each pair of fluorescent lamps, one lamp is powered by way of an inductive reactance means and one lamp is powered by way of a capacitive reactance means.

Abstract: An electronic ballast provides a high-frequency current-limited voltage between a pair of socket terminals. These socket terminals are adapted to receive and hold a rapid-start fluorescent lamp. A person coming in direct or indirect contact with one of these terminals may receive a hazardous electric shock.A self-oscillating electronic inverter is operable to provide the high-frequency voltage. To provide an output, this inverter has to be triggered into oscillation. However, except if current flows into both socket terminals, the inverter will automatically become disabled within 25 milli-seconds; whereafter it will not be re-triggered for about 1.5 seconds.With no current flowing, the magnitude of the high-frequency AC voltage is high enough to permit proper starting of a the rapid-start fluorescent lamp within a time span of 25 milli-seconds, but only after its cathodes have become incandescent. As soon as the lamp has started, lamp current flows into the socket terminals and through the fluorescent lamp.

Abstract: A fluorescent lamp operating system for a skin treatment apparatus comprises: (i) a plurality of pairs of fluorescent lamps for providing luminous radiation, each pair of lamps being adapted to be powered from 30 kHz/120 Volt by way of a high-Q series-resonant L-C ballasting circuit; (ii) a relatively low-power frequency converter connected with the power line and operable to provide power for heating the cathodes in these fluorescent lamps, thereby conditioning the lamps for easy starting; (iii) a relatively high-power frequency converter also connected with a power line and operable to provide the 30 kHz/120 Volt required for operating the plurality of pairs of fluorescent lamps by way of the high-Q series-resonant L-C ballasting circuit; and (iv) delay means operable to prevent the 30 kHz/120 Volt provided by the high-power frequency converter from being applied to the fluorescent lamps until after power has been applied to heat the lamp cathodes for at least one second.

Abstract: Subject invention relates to a fluorescent lamp ballast that is intended for safe and cost-effective use in lighting systems wherein the power to the various lighting fixtures is provided from a central source of relatively high frequency (Ex: 30 kHz) AC voltage. The ballast consists of a resonant series-circuit of an inductor and a capacitor--with the fluorescent lamp connected in parallel with the capacitor. Due to series-resonant action, if the lamp should happen to be non-connected or non-functional, and if proper precautions are not taken, the magnitude of the voltage developed across the capacitor may become so large as to cause damage to the circuit components and/or even to the source. To prevent such circuit damage, yet providing for a lamp starting voltage of suitably large magnitude and for an adequately long time, a Varistor voltage-limiting means is connected in parallel with the capacitor and a thermally actuated circuit breaker is connected in thermal contact with the Varistor.

Abstract: A sun tanning apparatus has an electronic operating system comprising: (i) a plurality of pairs of fluorescent lamps for providing tanning radiation, each pair of lamps being adapted to be powered from 30 kHz/120 Volt by way of a high-Q series-resonant L-C ballasting circuit; (ii) a relatively low-power frequency converter connected with the power line and operable to provide power for heating the cathodes in these fluorescent lamps, thereby conditioning the lamps for easy starting; (iii) a relatively high-power frequency converter also connected with a power line and operable to provide the 30 kHz/120 Volt required for operating the plurality of pairs of fluorescent lamps by way of the high-Q series-resonant L-C ballasting circuit; and (iv) delay means operable to prevent the 30 kHz/120 Volt provided by the high-power frequency converter from being applied to the fluorescent lamps until after power has been applied to heat the lamp cathodes for at least one second.