Abstract: A ballast feedback scheme including a single stage current feedback inverter. To avoid overboosting of the voltage impressed across a buffer capacitor only a portion of the high frequency lamp current is fedback to the buffer capacitor during both ignition and steady state operation of the lamp. Ignition of the lamp is well controlled.

Abstract: A fluorescent lighting system has: (A) a central power supply connected with regular power line voltage and including a number of power supply modules (e.g., eight), each such module having: (i) a parallel-resonant self-oscillating bridge inverter operative to provide a 35 kHz sinusoidal output voltage at a pair of primary output terminals; (ii) a tank-inductor and a tank-capacitor parallel-connected across the primary output terminals; and (iii) several (e.g., four) pairs of secondary output terminals, each connected with the primary output terminals via its own dedicated current-limiting sub- circuit; thereby to prevent a load connected with a pair of secondary output terminals from drawing more than a certain amount of power; thereby, in turn, to render each pair of secondary output terminals fire-hazard-safe; (B) a plurality of lighting fixtures (e.g.

Abstract: A circuit, such as a ballast circuit, includes a resonant feedback signal from an inverter that provides substantially linear operation of rectifying diodes. In one embodiment, capacitors coupled in series with respective lamps resonate with a first winding of a feedback transformer so as to generate a feedback signal on a second winding of the transformer. The feedback signal is effective to produce substantially linear operation of the rectifying diodes.

Abstract: In a circuit arrangement for operating a lamp comprising a power feedback and an antiboost switch disabling the power feedback for part of the time, the control of the antiboost switch is realized by means of a very simple and, hence, inexpensive control circuit.

Abstract: An electronic ballast has a unique inverter design which eliminates a large percentage of the required components, thereby simplifying and increasing the reliability of the ballast, while decreasing its costs. The ballast can operate both as a non-dimmable ballast and a dimmable ballast. The ballast can provide power for either two or four fluorescent lamps in a single light fixture, or for a plurality of such light fixtures connected in a daisy chain fashion. The ballast incorporates additional safety and protection features which are not available in existing ballasts, such removing the lethal danger of the 50/60 Hz power that is typically present at the lamps during lamp replacement. Furthermore, the electronic ballast supplies a constant high frequency output voltage to the light fixture independent of the frequency. There is very little distributed capacitance at the connections from the electronic ballast to the lamps.

Abstract: The invention proposes an apparatus and method for operating a gas discharge lamp (10) contained in a resonant circuit (L1, C1). A series connection is provided that is connected to a voltage source (14) and comprises a first semiconductor switch (12), an inductive element (L2) and a second semiconductor switch (13), with the resonant circuit (L1, C1) being connected at a connecting point (15) between the inductive element and the second semiconductor switch (13). If the gas discharge lamp (10) is in the non-ignited state, the first semiconductor switch (12) is continuously switched on and the second semiconductor switch (13) is at least approximately switched with the resonant frequency of the resonant circuit (L1, C1). In the ignited state of the gas discharge lamp (10), the two semiconductor switches (12, 13) are switched alternatingly and in push-pull operation with the operating frequency for operating the gas discharge lamp (10) in continuous operation.

Abstract: A broad range of brightness in a fluorescent lamp may be achieved by applying low-frequency, pulse-width modulated voltage or current to the lamp for a low level of brightness, or high-frequency voltage or current for a high level of brightness. Switching is provided to select between the two signals.

Abstract: A dimmer ballast or output drive circuit and a drive method for a high intensity discharge lamp utilizes an overwound loosely coupled transformer having a turns ratio of preferably about one to one with a peaking capacitor across the secondary output terminals of the transformer and in parallel with the HID lamp arc electrodes. A control circuit provides a variable frequency drive voltage to the primary of the transformer. The frequency of the output voltage is adjustably controlled above the peak load power frequency. The load power and hence the light output of the lamp varies according to the frequency of the output voltage permitting a user to adjustably dim the high intensity discharge lamp.

Abstract: The light-emitting-diode lamp comprises a set of light-emitting diodes, a rectifier and power converter circuit, and a power factor controller. The rectifier and power converter circuit converts ac or dc voltage and current from a power source to dc voltage and current supplied to the set of light emitting diodes. The rectifier and power converter circuit includes an electronic switch through which it is supplied with ac or dc voltage and current from the power source, and an inductor device including windings adapted to charge a capacitor with a voltage signal representative of the amplitude of the ac or dc voltage from the power source. The power factor controller is responsive to the voltage signal across the capacitor for controlling the electronic switch of the rectifier and power converter circuit in view of supplying dc voltage and current to the set of light emitting diodes while maintaining the power factor of the light-emitting-diode lamp equal to or close to unity.

Abstract: A pump supporting inductor (L1) is added to a half-bridge oscillator circ for a low-pressure discharge lamp (E) having a capacitive pump path, which inductor improves the pumping action of the pump path and its frequency response. Furthermore, an additional capacitor (C1) is connected between the pump path and the power supply path connected thereto, which capacitor acts as a trapezoidal capacitor in conjunction with the pump path and further improves the frequency response of the pump path.

Abstract: A frequency dependent controller utilizes a loosely coupled transformer, which controller is adapted to change the operating characteristics of the transformer by varying its operating frequency in accordance with the requirements of a load to be supplied with power. If the transformer is operated at a single frequency, the maximum current that can be delivered is limited by the reactance of the transformer. If the transformer is operated over a frequency range by the controller, the maximum current and other operating characteristics of the transformer are a function of both the magnetic shunt and its then current operating frequency. Frequency control of a loosely coupled transformer permits precision electronic regulation of the transformer's operating characteristics and is suitable for control of a variety of devices, such as gas discharge lamps, DC to DC converters, AC to DC power and high voltage supplies, motor control and variable heaters.

Abstract: A power-supply and control circuit is provided for driving a fluorescent lamp from a low-voltage direct current (DC) power source such as a battery. The circuit includes a converter that converts low-voltage DC to high voltage alternating current (AC). The converter includes a feedback ceramic step-up transformer that amplifies the AC signal to a level sufficient to illuminate the lamp, and also provides a feedback signal that can be used to monitor the resonance frequency of the transformer. The power supply and control circuit also includes a first feedback loop that regulates the lamp current amplitude and a second feedback loop that forces the converter to operate at the transformer's resonant frequency.

Abstract: A technology for eliminating acoustic resonance in a fluorescent lamp is disclosed in the present invention. The feature of the invention is to provide a harmonic compensating device to work with the fluorescent lamp and its relative peripheral circuits, such that current-dependent sources are provided to modulate the current in the lamp, thereby spreading the harmonic energy of the current in the lamp and eliminating acoustic resonance.

Abstract: An electronic ballast capable of linear and stepless light regulation that utilizes a chopped positive pulse passing through a limiting inductor and through two cathode coils of a fluorescent tube to a first mutual inductor and passing through a second transistor to excite the fluorescent lamp to radiate light. The luminosity is dependent upon the size of the portion of the positive pulse of the sinusoidal wave that is chopped. The chopped positive pulse utilizes the counter electromotive force generated by a first mutual inductor with respect to second and third mutual inductors to form semi-symmetrical resonance to maintain the pulse signals that pass through the fluorescent lamp to thereby continuously excite the cathode coils of the fluorescent lamp so that the latter always has the required luminosity. In this way, chopped power source waveforms are used to achieve linear light regulation so as to achieve zero dissipation, non-flashing during light regulation, and an increased light regulation range.

Abstract: A circuit arrangement for supplying a discharge lamp, comprising a converter for generating a high-frequency current with a frequency f from a supply voltage. The converter comprises at least one switching element which is rendered alternately conducting and non-conducting at the frequency f while the discharge lamp is being supplied. In addition a circuit portion I is provided for the low-frequency modulation of the power consumed by the discharge lamp through an adjustment of the conduction period of the switching element. As a result, instabilities in the discharge lamp plasma, such as striations and moding, are suppressed to a considerable degree.

Abstract: A switching circuit is provided for converting a DC voltage to an AC voltage required for driving an electroluminescent lamp. The switching circuit charges and discharges the electroluminescent lamp with a substantially constant current to thereby reduce peak currents and extend lamp life. A constant current discharge feature of the switching circuit results in a significant reduction in current consumption.

Abstract: The electronic ballast has a rectifier arrangement (1)--which is fed by AC power supply voltage (U)--with active step-up converter (SW2), a storage capacitor (C2), a network for limiting an inrush current and two outputs, at which a stabilized DC voltage (U+) referred to housing ground as reference potential (Uref) is output. An inverter (2) is connected to the rectifier arrangement, a load circuit (3) with at least one fluorescent lamp (La1 and/or La2) being assigned to said inverter on the output side. The inverter has a converter network (T1/1, T1/2, C1, SW3, SW4), preferably designed as a push-pull circuit, with two bridge paths, which, in the steady-state operating condition, are alternatively switched through to the reference potential. In this case, the switching network for limiting the inrush current comprises a limiting resistor (R1), which, in series with the storage capacitor (C2), is connected to reference potential.

Abstract: A circuit for supplying a discharge lamp, comprising a converter for generating a high-frequency current at a frequency f from a supply voltage and a circuit portion I for adjusting the power consumed by the discharge lamp through adjustment of the frequency. The circuit portion I is provided with a circuit portion II for low-frequency square-wave modulation of the frequency f and for the adjustment of the duty cycle of the square-wave modulation. As a result, the discharge lamp can be dimmed over a very wide range without striations or moding occurring and without undesirable shifts in the color point of the light.

Abstract: A ballast circuit for a gas discharge lamp includes a d.c.-to-a.c. converter circuit with circuitry for coupling to a resonant load circuit, for inducing a.c. current therein. The converter circuit comprises a pair of switches serially connected between a bus conductor at a d.c. voltage and a reference conductor, the voltage between a reference node and a control node of each switch determining the conduction state of the associated switch. The respective reference nodes of said switches are connected together at a common node through which said a.c. current flows, and the respective control nodes of the switches are connected together. A gate drive arrangement is provided for regeneratively controlling the first and second switches.

Abstract: Lamp voltage or current obtained from a self-oscillating converter is stabilized by a feedback circuit. Gates of the switching transistors are connected to output windings of a current transformer whose input current winding is in series with the resonant load lamp circuit. The lamp voltage or current is sensed, and the resulting signal is used to control current through an auxiliary control winding on the current transformer. Preferably, two opposite conductivity type control transistors are connected in parallel across the control winding, and low-pass filtered DC signals corresponding to the lamp voltage or current bias the control transistors.

Abstract: A compact fluorescent lamp and an electronic ballast therefor are mounted on a three-terminal base which can be fitted into a three-way-switched standard AC lamp socket, so as to be responsive to the three powered switch positions of the socket for generating three light output levels. The ballast includes an AC-to-DC conversion circuit which supplies a lamp driver including a DC-to-AC conversion circuit, an oscillatory circuit and a resonant circuit. In one embodiment the AC-to-DC conversion circuit includes a full bridge rectifier and a voltage doubler producing two operating voltage levels for the lamp driver and two frequency control voltage levels for the oscillator, the ballast generating three light output levels by using two operating voltages and two operating frequencies.

Abstract: The present invention is related to a micro-controller-operated high intensity discharge lamp ballast system. This system comprises the following elements: a boost pre-regulator means to convert a DC voltage into a high voltage DC bus to facilitate proper lamp power regulation, an inverter means to convert the high voltage DC bus into a high frequency FM modulated square wave voltage, a lamp matching network and filter means to convert the high frequency FM modulated square wave voltage into a high frequency FM modulated current facilitating the proper lamp power regulation, a lamp current and voltage sensing means to sense a lamp voltage and a lamp current across the high intensity discharge lamp and to feed the lamp voltage and lamp current into a micro-controller means adapted to facilitate proper functioning of the high intensity discharge lamp ballast system by means of sending a predetermined set of commands provided to monitor and control all elements of this system.

Abstract: The invention provides a soft starter device for lamps. The soft starter device includes a rectifying circuit for converting an AC voltage into a DC voltage which serves as a triggering signal; a high frequency voltage generating circuit for generating a high frequency voltage by an oscillation between two transistors; a high frequency output transformer electrically connected to the high frequency voltage generating circuit and having a primary coil and a secondary coil; a first capacitor for providing a momently high voltage to a lamp tube by generating a resonance together with the high frequency output transformer; and a control circuit having a charging circuit and a switch for grounding the secondary coil connected thereto or allowing the secondary coil to function normally. At the initial time of power supplying, the switch is turned on to ground the secondary coil, causing the primary coil being not able to function, such that only a current flows into the lamp tube to preheat the filaments thereof.

Abstract: A circuit arrangement for supplying a discharge lamp with a direct current includes input terminals for connection to a supply voltage source. A circuit portion (I) is coupled to the input terminals for generating a DC voltage from the supply voltage and is provided with output terminals between which the DC voltage is present during operation. A first branch comprising a first capacitor interconnects the output terminals and a second branch comprising a series arrangement of a second capacitor and an impedance shunts the first branch. A load branch shunts the series arrangement and comprises terminals for connecting a discharge lamp. The second branch also includes a diode so that a discharge lamp operated by way of the circuit arrangement stabilizes satisfactorily after ignition by a current supplied by the second capacitor to the lamp via the impedance.

Abstract: An electronic circuit providing independent operation and application of instant start voltages to each of a plurality of lamps. In a first embodiment, a circuit includes inductively coupled first and second inductive elements disposed on a single bobbin. A capacitive element is coupled between the first and second inductive elements to allow the inductively coupled inductive elements to operate independently when a lamp is removed from the circuit. A steady state strike voltage is generated at the lamp terminals from which a lamp has been removed. In another embodiment, a circuit includes a first circuit path including a first inductive element coupled to a first lamp and a second circuit including a second inductive element coupled to a second lamp. The first and second inductive elements are inductively coupled to effectively cancel flux generated while the first and second lamps are energized.

Abstract: A circuit for operating a discharge lamp from input terminals of a low frequency (f) supply voltage source with a rectifier coupled to the input terminals for rectifying the low-frequency supply voltage. A capacitor is coupled to the output of the rectifier. A DC-AC converter is coupled to the capacitor for generating a lamp current which comprises a DC component and a high-frequency AC component, the amplitude of the high-frequency AC component being modulated with a low frequency which is equal to twice the frequency f. An apparatus (V) adjusts the lamp power. The circuit parameters are chosen such that during operation the average amplitude of the high-frequency lamp current component is at least 500 times the amplitude of the low-frequency modulation of the high-frequency lamp current component with the power set for its maximum adjustable value. As a result, the discharge lamp can be dimmed over a wide range without striations occurring.

Abstract: The peak voltage of a periodic capacitive discharge, applied across first and second electrodes of the incandescent lamp, is about equal to the nominal DC voltage of the lamp multiplied by 3.2. The repetition rate of discharging, the extent of charging and discharging, and the value of the capacitance producing the periodic discharge result in the values of momentary peak and nominal temperature of the filament of the lamp being equal. Thereby, the value of peak luminous flux emission with respect to the nominal luminous flux emission of the lamp is several times greater. Where the discharge is periodic at a rate equal to about 14. HZ, then luminous flux emission by the lamp appears to the human eye to be continuously bright at an intensity equal to the peak value of luminous flux emission of the lamp, and the emission of the lamp is suitable for providing illumination. Emission of the lamp is suitable for providing emergency flashing where the discharge is periodic at a rate equal to about 1. HZ.

Abstract: A wax candle simulation device with random flicker electric circuitry, comprising at least two miniature light bulbs mechanically vertically closely arranged with the filaments therein arranged at an angle. The bulbs are contained within a flame shaped translucent housing and are connected to an electrical circuitry comprising two transistors, with one driving the other (inverter) with an external control and a switch between them set by resistor values. Additional resistors slow down light bulb shut down and the filaments are constantly pre-heated with a slow cool down, whereby the transition between the lighting of the light bulbs is very gradual. A single counter IC, creates the external driver circuitry with a portion of the IC providing a low stability oscillator and another portion operating as a counter with outputs connected to resistors. The other ends of the resistors are parallel and connected to the inverter.

Abstract: An electronic ballast lighting power control device including: a power switch controlled to provide a lighting power dim control signal to order the ballast providing an interrupted electric wave power output to the lighting fixture, and at least one electronic ballast respectively connected to the power switch and simultaneously controlled by the lighting power control signal of the power switch to provide an interrupted electric wave power output from the ballast to the lighting fixture, each of the at least one electronic ballast consisting of a filter, a rectifier, a power factor controller, a logic controller, an oscillator, and a protection circuit.

Abstract: A lighting apparatus includes a full-wave rectifier circuit for rectifying an AC voltage from a commercial power source, a smoothing condenser connected is series with an inductor and a diode between output terminals of the full-wave rectifier circuit, a light source unit containing a series circuit of light emitting diodes and connected in parallel with the smoothing condenser, a MOSFET connected in series with the inductor between the output terminals of the full-wave rectifier circuit, and a control circuit for performing switching control of the MOSFET. In particular, the control circuit is constituted such that a voltage across the smoothing condenser is set higher than a peak of an input voltage input to the smoothing condenser through the diode and equal to a total sum of forward voltage drops of the light emitting diodes at a time of igniting the light source, under the switching control.

Abstract: A ballast circuit for a gas discharge lamp includes a d.c.-to-a.c. converter circuit with circuitry for coupling to a load circuit, for inducing a.c. current therein. The converter circuit comprises a pair of switches serially connected between a bus conductor at a d.c. voltage and a reference conductor. The voltage between a reference node and a control node of each switch determines the conduction state of the associated switch. The respective reference nodes of the switches are connected together at a common node through which the a.c. current flows, and the respective control nodes of the switches are connected together. The load circuit has circuitry for connecting to a gas discharge lamp and comprises a piezoelectric transformer having a body and including a reference lead connected to one of the bus and reference conductors, an input lead coupled to the common node, and an output lead connected to the lamp.

Abstract: A snubbing network is provided for reducing electromagnetic ("EM") radiation from and power dissipation of a lamp discharge ballast. The snubbing network employs at least one active device. That device being a switch coupled in parallel with the modulating switch within a converter of the ballast. The snubbing switch, in conjunction with a current limiting inductor, and a voltage change rate limiting capacitor serve to substantially eliminate reverse recovery current within a freewheeling diode of the converter prior to closing the larger (modulating) switch. Reducing the reverse recovery current before closing the modulating switch helps minimize power dissipation during switch closure. A benefit of reduced power dissipation is a reduction in EM radiation from the lamp ballast to noise sensitive electronic components placed nearby.

Abstract: A neon discharging lamp lighting apparatus comprises a high frequency inverter of which an asymmetrical ratio of an output voltage waveform thereof is designated from 10 to 60% and a low pressure type neon discharging lamp connected to the high frequency inverter. Since the high frequency inverter circuit applies to the low pressure type neon discharging lamp a voltage having a waveform with an asymmetrical ratio for allowing rays of light free from luminance irregularity to be emitted, fringes can be prevented from taking place in rays of light emitted by the low pressure type neon discharging lamp. Thus, the low pressure type neon discharging lamp can operate as a high quality light source.

Abstract: A ballast for a discharge lamp comprises a smoothing capacitor, an inverter circuit including at least one switching device connected in parallel to the smoothing capacitor, a driving circuit for driving the inverter circuit, an activating circuit for activating the driving circuit, a resonance circuit including first and second capacitors and an inductor connected to output terminals of the inverter circuit, a discharge lamp connected to output terminals of the resonance circuit, a third capacitor connected in parallel to the discharge lamp. A fourth capacitor and first and second rectifying elements connected in series are connected in parallel to the smoothing capacitor. Between both terminals of the fourth capacitor and terminals for connection to an AC power source, a filter and a rectifier are inserted. A terminal of the first capacitor other than that connected to the inverter circuit is connected to a junction of the first and second rectifying elements.

Abstract: A monolithically integrated power device for driving electrical loads includes a power stage having a high-voltage bipolar transistor and a low-voltage auxiliary transistor cascade-connected and inserted between a first power supply terminal and a second power supply terminal of the device. The power device also includes a driver circuit for the power stage having an input connected to an input terminal of the device. In accordance with the present invention the device includes a circuit for protection thereof against an excessive temperature rise and controlling power down of the power stage.

Abstract: A ballast circuit for a gas discharge lamp with high speed gate drive circuitry comprises a resonant load circuit including a resonant inductance, a resonant capacitance, and circuitry for connecting to a gas discharge lamp. A d.c.-to-a.c. converter circuit induces a.c. current in the load circuit, and comprises a pair of switches serially connected between a bus conductor at a d.c. voltage and a reference conductor, the voltage between a reference node and a control node of each switch determining the conduction state of the associated switch. The reference nodes of the switches are connected together at a common node through which the a.c. current flows, and the control nodes of the switches are connected together. A gate drive arrangement for regeneratively controlling the switches comprises a driving inductor connected between the common node and the control nodes and mutually coupled to an inductor in the load circuit for sensing current in the circuit.

Abstract: A compact fluorescent lamp system includes a housing. An external base connector is mounted in the housing. The external base connector receives electrical power from an external source. A ballast unit is secured within the housing and electrically connected to the external base connector. The ballast unit controls the electrical power received from the external source. The compact fluorescent lamp system also includes a lamp unit. The lamp unit includes an amalgam ball pellet within the lamp unit, first and second lamp electrodes extending into the lamp unit, and a gas which breaks-down, permitting an electrical current to pass through the lamp unit. An inside wall of the lamp unit is coated with a material which fluoresces when the gas within the sealed lamp unit ionizes. The lamp unit also includes an extended wire connection having a first end electrically connected to one of the first and second lamp electrodes and a second end located near another point on the lamp unit.

Abstract: An electronic ballast circuit for operating an unlimited number of fluorescent lamps, which provides a high frequency, high open circuit voltage to start almost any fluorescent lamp and a constant current to the lamps once they are started. A single ballast is designed and rated to operate over a power range, simultaneously supplying a number of lamps. The ballast receives 120 VAC or higher voltage, 50 Hz/60 Hz input power, converts the AC input to a high voltage, high frequency sine wave voltage output to fluorescent lamps connected in series or parallel. One or more selected output capacitors provide current limiting to the lamps, which extends their life by reducing stress. The ballast includes a unique starter circuit that is simple, reliable and low in losses as compared with conventional ballasts.

Abstract: A method and apparatus for signaling promotional operation of a gaming device using existing fluorescent illumination lamps. An illumination lamp on a gaming device is operated continuously during normal operation, then flashed to signal promotional operation. Alternatively, an illumination lamp can be dimmed during normal operation, then operated at full brightness during promotional operation. To achieve flashing and dimming operation, a conventional starter is removed from a socket in a fluorescent lamp fixture and replaced with a controllable starter that fits into the same socket. The starter has a pair of wire leads for receiving a control signal for flashing or dimming the lamp. The controllable starter includes a starter circuit having a switch connected between two power terminals of the starter. When the switch closes responsive to the control signal, it shorts circuits the lamp, thereby extinguishing the arc and allowing preheat current to flow in the heating filaments of the lamp.

Abstract: The invention relates to a circuit arrangement for operating a discharge lamp with a high frequency current comprising a power feedback circuit and a electrode preheater. The circuit arrangement comprises an antiboost switch for disabling the power feedback circuit before the lamp has ignited and enabling the power feedback circuit after the lamp has ignited- In accordance with the invention the antiboost switch is also used to enable the electrode preheater before the lamp has ignited and to disable the electrode preheater after the lamp has ignited.

Abstract: In an externally controlled electronic ballast, a driving circuit which requires a dedicated supply voltage is provided for the purpose of driving an inventor half bridge. The driving circuit is constructed such that the inventor half bridge blocks when the supply voltage V.sub.cc falls below a threshold value UVLO. Via a self-holding controllable electronic switch and a Z diode DZ2, a voltage monitoring circuit draws the supply voltage V.sub.cc below the threshold value UVLO when an excessively high lamp voltage is detected. The ballast is thereby inactive. A current sensing path which leads via at least one filament of the low-pressure gas discharge lamp serves to detect a change of lamp. The current sensing path controls a further electronic switch, which is likewise connected to the supply voltage V.sub.cc of the driving circuit and can, when it conducts, draw said voltage further to frame than the first switch.

Abstract: A power supply or inverter circuit is provided for regulating power to electroluminescent lamps over a range of lamp sizes. The power supply may have an AC and/or DC input and includes at least one switch having a power input to be coupled to an electrical power source, a control input, and an output to be coupled to an electroluminescent lamp for being switched on and off to generate a drive signal to the lamp having a predetermined constant frequency and current level that is selectable over a range of frequency and current levels. A constant current mode controller has a control output coupled to the control input of the switch for turning the switch on and off so as to maintain a constant current level and frequency of the drive signal to the electroluminescent lamp substantially over its operating life. The voltage applied to the lamp is allowed to increase to a predetermined voltage limiting value in order to provide compensation due to aging of the lamp.

Abstract: In an inverter apparatus for a fluorescent lamp which is used as an original exposure lamp of a copy machine, a first secondary winding to which a choking coil and the fluorescent lamp are connected in series and a second secondary winding to which a capacitor is connected in series are formed on a secondary side of an inverter transducer, and a switching element for switching whether the first and second secondary windings are connected in series or in parallel and a diode bridge are further provided.

Abstract: A switched bridge circuit includes a low voltage to high voltage interface which selectively controls an input to a high side switch. A controller compares the voltage across the interface, the state of the high side switch, and the output of the circuit. If hard switching is detected by the controller, it latches the voltage across the interface thus keeping the high side switch on to allow the hard switching to occur. If soft switching is detected, the high side switch is kept off. A source follower is used to drive the high side switch so that the circuit output follows the interface output thereby avoiding oscillation. A falling edge detector for the output of the circuit uses the inherent parasitic capacitance of a high voltage device which also forms a bootstrap diode. When the output drops, the parasitic capacitance feeds a resistance which causes a driver to actuate. A second falling edge detector uses the inherent parasitic capacitance of the level shifter switch which is another high voltage device.

Abstract: An inverter circuit (10) for driving an electroluminescent lamp (14) reduces humming noise by discharging the electroluminescent lamp (14) through a resistor circuit (32). A charging circuit (36 or 38) charges the electroluminescent lamp (14) to a first voltage level during a charge cycle. The electroluminescent lamp (14) is subsequently discharged to a second voltage level through the resistor circuit (32), which prolongs the transition from the first voltage level to the second voltage level, thereby reducing the humming noise components of the inverter circuit (10).

Abstract: A lighting circuit for a discharge lamp comprises a DC power supply circuit having a coil and a capacitor at its input stage, a DC-AC converter for converting the output voltage of the DC power supply circuit to an AC voltage and supplying the AC voltage to a discharge lamp, ignition means for generating an ignition pulse to the discharge lamp, and control means for performing variable control on the output voltage of the DC power supply circuit 3. The control means 6 performs such a boosting operation as to boost the output voltage of the DC power supply circuit 3 to a predetermined voltage under a loadless condition while the ignition pulse generated by the ignition means 5 is supplied to the discharge lamp 11 to thereby light the discharge lamp 11. During the boosting operation, the ignition means 5 applies the ignition pulse to the discharge lamp 11, lighting the discharge lamp.

Abstract: The application of a piezoceramic resonator (PR), connected in parallel to a discharge lamp and in series to cathode filaments of a lamp, provides reliable means of preheating of cathode filaments facilitating a soft start of a fluorescent lamp. The piezoceramic resonator is a polarized piezoceramic element formed in a form of rectangular plate, disk, cylinder, etc. The linear size and shape of the PR determine the type of oscillation, electromechanical resonant frequency and frequency characteristics. The PRs with radial, contour or longitudinal oscillations are best suited for application to a piezoelectronic ballast. Piezoceramic resonators and filters as frequency-selective elements in measuring and radio communication instruments are widely used in weak alternating electrical fields, where the intensity of field does not exceed an order of volts per mm.

Abstract: A lighting circuit for a discharge lamp capable of improving the lighting performance of a discharge lamp with a simple circuit structure to thereby prevent a lighting failure at the end of the lifetime of the discharge lamp. The lighting circuit 1 comprises a DC power supply circuit 2, DC-AC conversion means 3 for converting a DC voltage output from the DC power supply circuit 2 to an AC voltage and supplying the AC voltage to the discharge lamp 5, a circuit element 6 (a switch element or a current limiting element) for blocking or limiting a current counter-flowing to the DC power supply circuit 2 from the DC-AC conversion means 3, and an inductive load 4 connected in series to the discharge lamp 5. A series circuit of a Zener diode 7 and a passive element 8 (a capacitor or a resistor) is provided in parallel to the circuit element 6, so that when the Zener diode 7 conducts, a rise in an auxiliary voltage for reignition is suppressed.

Abstract: An electronic ballast circuit includes an input section which rectifies, power factor corrects and filters an AC input voltage to provide a rectified signal. The electronic ballast circuit also includes an inverter section which receives the rectified voltage and switches the rectified voltage to provide an AC signal to a resonant load circuit. The input section includes a resonant tank circuit which provides a high frequency current to the inverter to soft switch the switches within the inverter. In the input section, an inductor is placed on the AC side of a diode bridge rectifier advantageously allowing the removal of several prior art ballast circuit components since placing this portion of the power factor correction (PFC) circuit within the input circuit on the AC side of the diode bridge rectifier allows the bridge rectifier to perform both the rectification and current blocking functions.

Abstract: A system of igniting a gas discharge device having spaced electrodes immersed in a gas, at voltages below the required starter ignition voltage for cold cathodes. A square wave alternating voltage source of between about 75 kHz and 4 MHz is applied directly to the gas discharge device so that the voltage on the spaced electrodes reverses its polarity more rapidly than the pattern of electron and ion density in the gas can shift.