Abstract: Provided are a pulse width modulation (PWM) apparatus and a light source-driving apparatus including the PWM apparatus. The PWM apparatus includes a voltage division part, a capacitor part, a first operational amplifier, a first noise reduction part, and a second operational amplifier. The voltage division part divides and outputs an input voltage. The capacitor part charged by an input current or discharged for provides a charge voltage. The first operational amplifier operates according to a result of comparing a divided voltage output from the voltage division part with the charge voltage output from the capacitor part. The first noise reduction part removes a high frequency noise of the divided voltage. The second operational amplifier converts a signal generated from the capacitor part into a pulse width modulation signal by a dimming control signal.

Abstract: A method and system for reducing and/or eliminating striations from gas discharge lamps powered by an electronic ballast charges a capacitive energy device, which is coupled in parallel with the lamp, when the capacitive energy device detects that a predetermined lamp voltage condition has been satisfied. The system/method supplements the current supplied to the lamp by the electronic ballast with current supplied from the capacitive energy device when the predetermined lamp voltage condition is not satisfied. The supplemental current supplied to the lamp creates a harmonic-rich lamp current waveform that reduces and/or eliminates striations.

Abstract: An inexpensive electric discharge light-regulation matching circuit for use with a standard light regulator to regulate the light of an electric discharge without causing flickering is disclosed to include a resonance unit, which comprises a first capacitor and a second capacitor connected in series and a first inductance connected in parallel to the first capacitor and second capacitor, a converter circuit connected to the resonance unit for converting an alternating current into a direct current, a half-bridge output unit, which comprises two electrically controlled switches connected in series to the converter unit with the respective control end respectively connected to a respective oscillation unit, and a voltage feedback unit, which is connected to the half-bridge output unit and the converter unit and comprises a second inductor, a third capacitor and a fourth capacitor that are connected in series.

Abstract: Disclosed is an energy-conserving device for an illumination system. The energy-conserving device is connected between a power supply of and a lighting assembly of the illumination system. The energy-conserving assembly provides a first switch, a ballast, and a compensating capacitor. The ballast is connected between the power supply and the lighting assembly, and connected between the first terminal and the second terminal of the first switch. The compensating capacitor is connected between the power supply and a third terminal of the switch. The energy-conserving device may further include a resistor and a second switch which are connected in parallel with the ballast. The energy-conserving device can be coupled to a conventional illumination system and is of energy-conserving, a low cost and a long lifetime.

Abstract: An electronic ballast is provided for converting an AC voltage and current, supplied by a power source such as a power line, to an alternating square-wave voltage and current having the same frequency, for supply to a discharge lamp. The ballast includes at least one capacitor, bridge switches and high-frequency duty-cycle switches. The bridge switches and the high-frequency duty-cycle switches cooperate to successively electrically connect the capacitor in parallel with the power source, electrically connect the capacitor in series with the power source and the discharge lamp, and to regulate the current provided to and from the capacitor to drive the discharge lamp with a desired square-wave voltage and current at the line frequency.

Abstract: A ballast for a gas discharge lamp circuit has a d-c output which contains three series-connected diodes connected across the output terminals, a pair of capacitors connected from different respective nodes of the diodes to respective ones of the output terminals, and a resistor connected between two of the diodes. The resistor increases the circuit power factor to greater than 0.95.

Abstract: A low cost circuit addition in the form of a capacitor of suitable value provides effective starting and operation of rapid start, preheat, and instant start fluorescent type gas discharge lamps along with their standard A.C. operated ballast transformer auxiliary devices at reduced power levels to achieve energy conservation with a concomitant reduction in light output and can usefully employed in illuminated areas where a reduction in lighting level would not effect the utility of that particular area. The capacitor is connected in series with the ballast primary winding and is of such value as to cause ferro-resonance to occur in the ballast transformer primary circuit, thereby providing a voltage magnification effect to aid the lamp starting, or ignition, process i.e., during the time interval between circuit energization and production of a stable arc, and to thereafter operation of the lamp with reduced arc current.

Abstract: A circuit arrangement for A.C. operation of gas discharge lamps comprises a full-wave rectifier (1) connected to an alternating voltage source. The direct voltage is supplied to a combinatorial circuit part (3 to 8) in the form of a direct voltage converter, to which is connected a bridge circuit (9) which comprises four thyristors. The transverse branch of the bridge circuit includes the lamp (5). The full-wave rectifier (1) is followed by a smoothing capacitor (2) and an electronic switching element (14) is connected parallel to the bridge circuit (9). The switching element is switched to the conducting state in the vicinity of the zero passages of the input alternating voltage. As a result shortcircuits in the bridge circuit are avoided.

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 high intensity discharge lamp operable from an AC potential source includes an arc discharge tube having a pair of oppositely disposed main electrodes therein and an associated external starting electrode, all disposed within a sealed envelope having an affixed base with a circuit means including a negative potential blocking device coupling the starting electrode to the AC potential source.