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 causing 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 within 25 milli-seconds; whereafter it will not be re-triggered for about 1.5 seconds.

Abstract: For a starting device to acquire an ability to start a discharge tube efficiently, allow the light from the discharge tube to be regulated effectively over a wide range, and fit versatile use with discharge tubes of a varying kind, this invention causes the frequency of pulses of a fixed duty ratio issued by pulse generating means to be freely adjusted by adjusting means and consequently enables high-voltage applying means to apply a high voltage of a frequency proper for the pulses to the discharge tube and effect efficient and stable start of the discharge tube. Since the frequency of high voltage for application to the discharge tube is adjusted by the adjusting means, the regulation of light is attained over a wide range and the starting device itself is enabled to fit versatile use with discharge tubes of a varying kind.

Abstract: An overvoltage shutdown circuit for use with high voltage excitation supplies for gas discharge tubes is described. In one embodiment, a spark gap is placed between the secondary output windings of a resonant conversion output transformer. In a second embodiment, a sense conductor is placed in proximity to the high voltage output windings of the resonant conversion transformer to receive a spark in the event of overvoltage on the output. A sensed spark causes a latching circuit to stop the resonant conversion thereby protecting the power supply from a potentially damaging overvoltage situation.

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: To provide for automatic disconnect upon failure of a filament of one (E2) f the electrodes of a fluorescent lamp, an output terminal (P1) of a power rectifier is connected through the filament to a supply terminal (P3) of a push-pull frequency generator formed by two transistors (T1, T2). The fluorescent lamp (LP) has its other electrode (E1) connected to a common terminal between two transistors (T1, T2) of the high-frequency generator. A series resonance circuit (L1, C6, C8) is capacitor-coupled (C7) to the lamp. Upon failure of the filament of the first electrode (E2), or removal of the lamp from its lamp sockets, power supply to the transistor oscillator or frequency generator circuit is interrupted, so that the oscillator is deenergized; upon insertion of an operative lamp in the lamp circuit, the circuit is closed so that the fluorescent lamp is automatically started by the push-pull oscillator (3) formed by the two transistors (T1, T2) and associated circuitry.

Abstract: A starter controller for a multiple parallel ballast for high pressure sodium lamps detects lamp "drop-out" or 'cycling" and enables restarting of the lamp if the drop-out was causded by line transients of a level sufficent to cause normally operating lamps to drop-out. If the detected lamp drop-out was caused by normal end-of-life conditions, the controller does not allow restarting of the lamp. In one embodiment, the starter controller constantly monitors the voltage across the lamp terminals. When lamp drop-out occurs, this voltage rises rapidly to the ballast open-circuit secondary voltage. This voltage is detected by a level detector and rate detector which then processes lamp voltage level and rate of change of voltage after the initial drop-out is sensed.

Abstract: Circuitry for limiting a high frequency current through a load including a DC voltage source connected to a circuit ground; an inverter for converting the DC voltage to the high frequency current, the inverter being connected to circuit ground; a chassis containing the voltage source and the inverter where the chassis is connected to earth ground and where earth ground and circuit ground are at different electric potentials; sensing circuitry connected between earth ground and one of the output terminals of the voltage source to establish a current path from earth ground to the one output terminal of the voltage source to thus monitor any high frequency current which may flow through a person, for example, connected between one of the output terminals of the inverter and earth ground; and limiting circuitry for limiting the high frequency current through the person in response to the current through the person exceeding a predetermined limit.

Abstract: The present invention relates to a method and apparatus for driving discharged lamps and which is adapted to maximize the luminous efficiency of a discharged lamp and its associated electronic driving apparatus. This is accomplished through the power sourcing characteristics of the driver, by causing the required power to dissipated while maintaining the power factor in the lamp as near unity as possible with the real components available for the implementation of the apparatus.

Abstract: A mounting assembly for a light bulb includes a soft start-up circuit as well as a DC-to-AC converter in order to prolong bulb life. In addition, the mounting assembly includes a removable socket to facilitate changing the bulb. When the socket is rotated from an "engaged" position for removal, an interlock causes power to be interrupted at a remote location from the mounting assembly. In addition, conducting portions of the mounting assembly are remotely located to reduce the possibility of accidental contact during socket installation and removal.

Abstract: A discharge lamp lighting system including at least one switch device connected between a d.c. power supply and a discharge lamp which is turned on by a high frequency power generated through turning-on and -off of the switching device. In the discharge lighting system, the discharge lamp lighting operation is allowed to start when the d.c. power supply voltage reaches a predetermined voltage value A or over, and the discharge lamp lighting operation is stopped when the d.c. power supply voltage lowers smaller than a predetermined voltage value B, where the values A and B take a relation that B is smaller than A.

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: The present invention uses a variable frequency oscillator to drive a primary resonant converter output transformer circuit for exciting gas discharge tubes. The combination of the impedance of the resonant conversion circuit along with the impedance of the driven gas discharge tube taken in combination with the frequency of the variable oscillator will determine the output voltage of the circuit. By varying the frequency of the oscillator, the optimal output voltage and hence the optimal brightness of the gas discharge tube may be selected. At the optimal output voltage, the frequency of the switching supply may create an undesirable or desirable "bubble effect" in the gas discharge tube. An optional secondary frequency may be combined with the frequency of the variable frequency oscillator to create or eliminate the bubble effect according to the esthetic desires of the user.

Abstract: A d.c. voltage supply circuit including a flyback converter having an inductor which is alternatingly charged through an electronic switch and discharged via a diode onto a capacitor. The output voltage of the flyback converter is continuously monitored. If a threshold value is exceeded, the electronic switch, which is mounted in an input line of the flyback converter, is changed into the off-state. The off-state of the electronic switch is terminated as soon as the output voltage has again fallen below the threshold value. Loads requiring a specific d.c. voltage may be connected to different supply voltages without the need of changeovers. The circuit offers a high security in view of overvoltage from the power network. It is self-monitoring and protects the connected load.

Abstract: A lamp start, hot-restart and operating circuit for a high wattage, high intensity discharge lamp includes cascaded resonant circuits with capacitors and series-connected inductors connected to an AC source. A pulse circuit including two pulse transformers supplies streamer-forming current, the secondary windings of the pulse transformers being connected in series with the lamp. When the lamp commences normal operation, the operating current energizes a relay to remove the capacitors and pulse circuit from the operating circuit, allowing the inductor to function as the lamp ballast.

Abstract: A dimmer control circuit having time constant regulating means provided in a multivibrator for regulating the load time ratio of the output pulse signal of the multivibrator to control ON, OFF the voltage of a battery applied to a lamp by the output pulse signal to thereby regulate the luminous intensity of the lamp comprising stopping means provided in the multivibrator for operating near the end of the regulation in a direction for increasing the luminous intensity of the lamp by the time constant regulating means and stopping the operation of the multivibrator. Thus, the dimmer control circuit can stop the operation of the multivibrator near the end of regulation in a direction for increasing the luminous intensity of a lamp to control the connection of a battery directly to the lamp with a fine current.

Abstract: One or more power dimmers have a preshaped phase controlled input signal connected to their control input. The preshaped phase controlled input signal is generated from the output of a master dimmer having conventional phase control circuits operated from a manual or other control. A relay having contacts in the output circuit of the power dimmers is opened in response to the reduction of the phase controlled input signal to a value less than a given value. In an alternative embodiment, the power dimmers are replaced by an interface circuit which produces a variable frequency, pulse width modulated or other signal.

Abstract: A starting, hot restarting and operating circuit includes a pulse circuit for applying high voltage pulses to an HID lamp for starting or hot restarting. After a set interval of pulses if the lamp has not ignited, the pulse circuit is turned off for a selected inactive interval after which pulses are applied to the lamp again. If ignition does not occur after several active/inactive cycles, the circuit is deactivated until reset by turning the power off and on.

Abstract: A fluorescent lamp operating device having a power supply, a circuit for converting the output power from the power supply into a high-frequency power, a lighting circuit connected to a secondary side of a transformer of the high-frequency power converter circuit to light a fluorescent lamp, a circuit for preheating the filament of the fluorescent lamp, a switch circuit including diodes and at least one transistor connected in series with the fluorescent lamp in the lighting circuit, and a control circuit for turning off the transistor for a predetermined period when the power supply is turned on thereby turning off the lighting circuit to actuate the preheating circuit during this period. The control circuit turns on the transistor at the end of the predetermined period to thereby actuate the lighting circuit.

Abstract: A dimming circuit adjusts the light output of a lamp by controlling the current flow in the lamp that is connected to a transistor, through turning on and off the transistor with a predetermined timing which is changed by the control signal from a control signal generating circuit. The dimming circuit has a protective circuit for applying an off-state command signal to switch the transistor to the off-state by detecting an excess current flowing in the transistor when an input signal is applied as a control signal for switching the transistor to the on-state.

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.

Abstract: A discharge lamp operating device having a high frequency inverter is discharged. Connected to a secondary winding of an oscillation transformer of the high frequency inverter is a discharge current supply circuit having a switch for controlling supply of a discharge current to dim a fluorescent lamp. An electrode heating circuit is connected to secondary windings of the transformer to continuously heat electrodes. An oscillation frequency of the inverter is controlled such that it increases as a dimming factor is high and decreases as the dimming factor is low. A capacitor is connected in series with a path of an electrode heating current in the electrode heating circuit so that the heating current is increased when the dimming factor is high and decreased when it is low by utilizing a frequency dependency of an impedance of the capacitor.

Abstract: In a series-resonant-loaded inverter-type electronic ballast for two rapid-start fluorescent lamps, in order to meet requirements for safety from electric shock hazard, as well as to protect the inverter circuit from over-load, means are provided by which the proper connection to the ballast of the fluorescent lamps is sensed by way of detecting the proper flow of lamp cathode heating currents. Then, after the circuit is initially turned on and if one of the lamp cathodes were to draw substantially less current than normally called for, the inverter circuit is shut down immediately. On the other hand, if each lamp cathode draws the expected amount of cathode heating current, the inverter circuit is not shut down immediately, but is allowed to operate for a time at least long enough to permit proper starting of the rapid-start fluorescent lamps.

Abstract: A shut-off device is provided for an inverter which feeds at least one discharge lamp, the shut-off device operable to shut-off the inverter in limiting cases and remaining in this condition until a lamp replacement. The shut-off device flips into its normal condition when a holding current in a monitoring circuit falls below a flyback limit value. In order to keep the losses as low as possible, the monitoring circuit is dimensioned high-resistant and a separate holding circuit is provided, the separate holding circuit having a controlled dependency on the low control current in the monitoring circuit. In the disconnect case, the control current also suffices to hold the shut-off device in the disconnect condition when an electrode is broken.

Abstract: Subject high-frequency lighting system comprises the following principal component parts:(a) a power-line-operated power supply operable to supply a high-frequency (30 kHz) output voltage;(b) a plurality of lighting fixtures--with each such fixture comprising one or more gas discharge lamps and series-resonant ballasting means operative to derive the requisite lamp operating voltages and currents from the power supply's high-frequency voltage output; and(c) a bus wire means operative to distribute said high-frequency voltage from the power supply and to each of the fixtures. To protect against circuit failures, which might occur due to excessive socket voltages resulting upon removal of a lamp or toward end-of-lamp-life, a Varistor voltage-limiting means and a self-latching circuit breaker means are used with each series-resonant ballast.

Abstract: The invention relates to an inverter, in particular, for the feeding of a discharge lamp, comprising a rectifier, a charging regulator with a charge inductor, a charging diode, a charging switch, as well as a charging condenser. An alternating voltage converter is provided with at least two alternately through-connected switches, designated as primary and secondary switches, which are in series connection parallel to the charging condenser. A simple control of the charging switch is provided with an automatic blocking of the charging switch upon disconnection of the alternating voltage converter. For this purpose the control of the charging switch by a square wave voltage is synchronized on one of the switches of the alternating voltage converter.

Abstract: Subject invention relates to an inverter-type electronic fluorescent lamp ballast wherein a series-resonant LC circuit connected across the inverter's output is used for matching the inverter's operating characteristics to those of the fluorescent lamp--the fluorescent lamp being connected in parallel with the tank-capacitor of this LC circuit.More particularly, the invention relates to the use of a Varistor coupled in parallel with this tank-capacitor, thereby limiting the voltage developed thereacross to a magnitude suitable for proper lamp starting. Moreover, by providing for means whereby the inverter shuts itself off in case current flows through this Varistor for a longer time than it should take for a fluorescent lamp to start, inverter overload protection is obtained. Without such overload protection the inverter would self-destruct in case the fluorescent lamp failed to start or if it were removed from the circuit.

Abstract: Subject invention relates to an inverter-type electronic fluorescent lamp ballast wherein a series-resonant LC circuit connected across the inverter's output is used for matching the inverter's operating characteristics to those of the fluorescent lamp--the fluorescent lamp being connected in parallel with the tank-capacitor of this LC circuit. In particular, the invention relates to the use of a Varistor coupled in parallel with this tank-capacitor, thereby limiting the voltage developed thereacross to a magnitude suitable for proper lamp starting. Moreover, by providing for means whereby the inverter shuts itself off in case current flows through this Varistor for more than about one second or so (which is the maximum length of time that it should normally take for a fluorescent lamp to start), inverter as well as Varistor overload protection is obtained.

Abstract: A remotely controlled dimming solid state ballast system for gas discharge lamps adapted to respond to external control signals is disclosed which includes the ballast itself along with integral controls for interfacing with an external addressing control system, which may be a powerline carrier system. The external control system includes a signal receiver for receiving, and recognizing remotely transmitted control signals addressed to said ballast. An output device is provided for generating an output control signal modulated in response to the control signals to provide the desired control setpoint of the lamps controlled by the ballast or to turn the lamps on or off.

Abstract: A two-wire electronic dimming ballast arrangement for one or more gas discharge lamps is disclosed which includes an inverter driven by a variable pulse width electric power and a control system for modulating the pulse width of the variable pulse width square wave electric power driving the inverter. A unique distortion suppression system is provided for suppressing current abberations and achieving substantially a unity power factor.

Abstract: With many fluorescent lighting fixtures, the voltages required at the sockets to start and operate the fluorescent lamps are so high as potentially to constitute a substantial electric shock hazard to persons having to service such fixtures. To mitigate this hazard, whenever socket voltages exceed certain levels, protective measures have to be provided.Subject invention constitutes an electronic means for removing the socket voltages from a fluorescent lighting fixture in cases where a lamp is removed from one of its sockets.The invention relates to situations wherein inverter-type ballasting is being used, and involves the use of an electronic means for disabling the inverter whenever the ballast has provided the relatively high output voltage required for lamp starting for a period longer than that normally required for the lamps to start. However, if the lamps do start within the normally required time period, thereby causing a reduction in the output voltage, the disabling of the inverter will not occur.

Abstract: A power saving device for use in a power supply circuit has an electronic switching element which is turned on when a pushbutton normally open type switch is closed to actuate a DC-DC converter and a fully electronic control system which forces the electronic switching element into the non-conduction state after a predetermined time interval, to interrupt the connection of a low-voltage power source to the DC-DC converter.

Abstract: In an electronic flash device of the type having a power supply unit comprising a low DC power supply and a DC-DC converter and an IC memory which can maintain its stored information even if when a power supply switch is turned off, there are provided a backup capacitor which can maintain the normal and stabilized operation of the IC memory which is connected to the power supply even when the voltage of the power supply drops to such a level that the normal and stabilized operation of the IC memory cannot be maintained; a voltage detecting means for detecting the voltage across the power supply; and a control circuit which responds to the output signal from the voltage detecting means so as to control the operation of the DC-DC converter.

Abstract: In a strobo apparatus comprisinga power source part (A) containing a low voltage battery and a DC-DC converter circuit,a flashing part (B) containing a main capacitor and being separably connected with the power source part, and also hasa detecting means for detecting the said separation of the flashing part. By utilizing the output of the detecting means, the operation of the DC-DC converter circuit is compulsorily stopped, accordingly, waste of battery is eliminated and unnecessary high insulation against useless high tension during the separation of two parts can be dispensed with.

Abstract: An energy-efficient ballast or energizing circuit for fluorescent lamps which is relatively uncomplicated and which can be manufactured relatively simply and inexpensively. An on-off switch and dimming means are connected in a low-voltage portion of the circuitry to permit less expensive wiring to be utilized. A base-driven, high frequency push-pull transistorized inverter circuit is utilized for energizing the lamps. The inverter drive is pulse width modulated to effect dimming, and to save energy additional transistor circuitry is provided for ensuring rapid turn-on and turn-off of the inverter transistors. A photo-responsive means senses ambient light and lamp light at a surface being illuminated by both and controls pulse width in accordance therewith. Thermostat means are mounted on the heat sinks of the inverter transistors and are connected in parallel with the on-off switch to effect shut-off if overheating occurs.

Abstract: For protection against potentially serious electric shock hazard to a person removing and/or replacing a fluorescent lamp in a fluorescent lighting fixture having an inverter-type electronic ballast, a special protection circuit is provided as part of this ballast.This protection circuit operates to disable the ballast inverter within about one second after a fluorescent lamp is removed from at least one of its sockets, thereby removing the potentially hazardous voltage present at the fixture's lamp sockets.

Abstract: The invention relates to a device for regulating the power in electrical apparatuses, especially fluorescent lighting fittings. To each apparatus (6) is connected an inverter (1-5, 7-11; 12; 13) in which the control circuit of the oscillator transistor (1) is provided with an adjustable RC circuit (8, 9).The power of a plurality of apparatuses included in the same group can be adjusted through one pair of conductors by connecting in parallel with the RC circuit (8, 9), on one hand, the contacts of a relay (10) and, on the other hand, an opto-insulator (11) whereby the relay (10) is connected to one conductor of the pair of conductors and the opto-insulator (11) to the other conductor.

Abstract: An intrinsically safe lighting system for energizing fluorescent lamps and the like in potentially flammable or explosive atmospheres is disclosed wherein one or more intrinsically safe power supply modules embody current monitoring and diverter circuitry, operable, upon the occurrence of abnormal circuit conditions such as a short or open circuit, to interrupt the lamp power supply and divert energy therefrom so rapidly that non-intrinsically safe sparking and ignition of the flammable atmosphere is avoided.

Abstract: A light dimmer control system for controlling the current supplied from a DC power source to high power illuminating lamps. The current fed to the lamp is controlled by manually setting the width of the pulsed output of a pulse width modulator by means of a potentiometer or the like appropriately connected to the pulse width modulator. The output of the pulse width modulator drives an output driver circuit which is connected in series with the current path to the lamp. The lamp power is provided from a DC source which is controlled by the output driver circuit in series with the lamp. The power for the semiconductor components of the DC controller, which includes the pulse width modulator, is provided from the same DC source and stepped down by a DC-DC converter. A logical control circuit is employed which enables the energization of the system only when both the polarity of the DC input supply is correct and the low voltage DC is on, thereby minimizing the possibility of damaging system components.

Abstract: A flash device for photography includes a DC/DC converter for boosting a DC power source voltage and applying a voltage to a main capacitor for supplying an energy for driving a flashlight tube. The converter has control means operative in response to the trigger operation by a start operating switch to detect any reduction in the charging current of the main capacitor and stop said operation. The flash device is provided with another switch means for enabling the operation of the converter independently of the start operating switch. Said another switch means is operative to operate the converter until the charging voltage of the main capacitor reaches a sufficient value to drive the flashlight tube.

Abstract: An electronic drive system for a discharge lamp is disclosed wherein the switching frequency of the chopper is reduced until the lamp striking voltage has reached about 70% of its rated value. The system includes a chopper transistor, a control for varying the transistors duty cycle and a smoothing inductance, freewheeling diode and smoothing inductor to smooth the chopper output. Current limiting is provided to prevent overcurrent within the chopper transistor, smoothing inductor or lamp.

Abstract: A flashlamp drive circuit 10 using an unsaturated transistor Q1 as a current mode switch to periodically subject a partially ionized gaseous laser excitation flashlamp 20 to a stable, rectangular pulse of current from an incomplete discharge of an energy storage capacitor C1. A monostable multivibrator MV1 sets the pulse interval, initiating the pulse in response to a flash command by providing a reference voltage to a non-inverting terminal of a base drive amplifier AV1; a tap on an emitter resistor R2 provides a feedback signal sensitive to the current amplitude to an inverting terminal of amplifier AV1, thereby controlling the pulse amplitude. The circuit drives flashlamp 20 to provide a square-wave current flashlamp discharge.

Abstract: A device for charging a charging capacity from an a.c. source via a transformer and rectifier by using at least one auxiliary capacitor for buffer-charging of the charging capacitor is disclosed. The charge of the capacitor is used for example for charging an accumulator and flashing a light source. Change of the capacity of the auxiliary capacitor makes it possible to regulate the charging characteristic of the charging capacitor in charging an accumulator and to regulate the flash character, i.e. intensity and flash frequency, in case of the charging capacitor being discharged through a flash bulb via a thyristor.

Abstract: A low cost high frequency electronic dimming ballast for gas discharge lamps is disclosed which eliminates the need for external primary inductance or choke coils by employing leakage inductance of the transformer. The system is usable with either fluorescent or high intensity discharge lamps and alternate embodiments employ the push-pull or half-bridge inverters. Necessary leakage inductance and tuning capacitance are both located on the secondary of the transformer. Special auxiliary windings or capacitors are used to maintain necessary filament heating voltage during dimming of fluorescent lamps. A clamping circuit or auxiliary tuned circuit may be provided to prevent component damage due to over-voltage and over-current if a lamp is removed during operation of the system.

Abstract: An improved output configuration for a multiple-lamp electronic ballast system. The output includes a differential transformer having a primary adapted to be coupled in a first loop including a first filament filament drive winding and feedback winding and a secondary adapted to be coupled in a second loop that includes a second filament, filament drive winding and feedback winding.The improvement allows the entire ballast to be shut down when a lamp has been removed thereby avoiding aberrant oscillator operation under abnormal, yet predictable, lamp load conditions.

Abstract: Starting and operating circuit for gaseous discharge lamps has device for quickly re-starting extinguished lamps while still hot. Circuit comprises a source of alternating current, an inductive regulator ballast having its input connected to the alternating current source, and a gaseous discharge lamp connected to the output of the ballast, a sine wave oscillator circuit having its input connected to the current supply and having its output connected to a transformer connected in series between the ballast and the lamp for stepping up and applying voltage to a lamp, and a positive temperature coefficient resistor (PTCR) connected between the alternating current source and the oscillator circuit for reducing power to the oscillator circuit when the lamp is inoperative or absent.

Abstract: The invention relates to a d.c. to a.c. converter comprising two transistors (22, 25) and an output transformer (21). This converter also includes an auxiliary d.c. voltage source (43) and is provided with an auxiliary winding (40) of the transformer (21) which connects the base of one transistor (22) to the base of the other transistor (25).According to the invention, the combination of the auxiliary d.c. voltage source (43) and a control circuit of the two transistors (22, 25) comprises a current blocking means (44) such that the converter can be supplied with a pulsed d.c. voltage. Consequently, that converter can be operated from a low frequency a.c. voltage mains via an auxiliary full-wave rectifier (5 to 8), which does not need to have a high value smoothing capacitor.

Abstract: The invention relates to an arrangement comprising a gas and/or vapor discharge lamp (5) which includes a discharge tube (5a). An electronic auxiliary device (10-16) is arranged in parallel with the discharge lamp (5). This auxiliary device ensures that in the operating condition the lamp is shunted briefly during each half cycle of the power supply.With an arrangement according to the invention, the lamp (5) is of a type in which the discharge tube (5a) has a temperature of at least 200.degree. C. in the operating condition. The auxiliary device is connected to sensor elements (20; 25-28) which ensure that the lamp (5) is not shunted in the period of time in which the lamp (5) has not yet reached the operating condition. This achieves reliable starting of the lamp.

Abstract: Subject invention relates to an inverter-type electronic fluorescent lamp ballast wherein a series-resonant LC circuit connected across the inverter's output is used for matching the inverter's operating characteristics to those of the fluorescent lamp--the fluorescent lamp being connected in parallel with the tank-capacitor of this LC circuit. In particular, the invention relates to the use of a Varistor coupled in parallel with this tank-capacitor, thereby limiting the voltage developed thereacross to a magnitude suitable for proper lamp starting. Moreover, by providing for means whereby the inverter shuts itself off in case current flows through this Varistor for more than about one second or so (which is the maximum length of time that it should normally take for a fluorescent lamp to start), inverter as well as Varistor overload protection is obtained.

Abstract: Subject invention relates to an inverter-type electronic fluorescent lamp ballast wherein a series-resonant LC circuit connected across the inverter's output is used for matching the inverter's operating characteristics to those of the fluorescent lamp--the fluorescent lamp being connected in parallel with the tank-capacitor of this LC circuit.More particularly, the invention relates to the use of a Varistor coupled in parallel with this tank-capacitor, thereby limiting the voltage developed thereacross to a magnitude suitable for proper lamp starting. Moreover, by providing for means whereby the inverter shuts itself off in case current flows through this Varistor for a longer time than it should take for a fluorescent lamp to start, inverter overload protection is obtained. Without such overload protection the inverter would selfdestruct in case the fluorescent lamp failed to start or if it were removed from the circuit.