Abstract: A method and apparatus suited to operate a lamp in a manner that addresses the problems of the prior art. The luminosity at each lamp is individually monitored to maintain an optimum lumen level for the lamp. The sensor used to monitor the lamp is powered by the same light source(s) it detects.

Abstract: Intermittent electrical power is applied to a lamp ballast to achieve reliable ignition within specifications of the related hardware. The operating state of the lamp is sensed to facilitate application of the power during lamp ignition. Control circuitry associated with a ballast is operable to interrupt the ionizing potential once prior to the lamp's reaching an igniting state. That is, an ignition cycle associated with the ionizing potential may be intermittent, having an interruption, or “off” period. For example, a ten-second ignition cycle may include a one-second “on” period, followed by nine-seconds of no ionizing potential. The ignition sequence and associated intermittent ionizing potential supply will repeat as necessary to achieve lamp ignition. The intermittent nature of the ballast output enables the lamp to achieve an ignited state in manner that obviates the need for large, damaging voltage spikes.

Abstract: Intermittent electrical power is applied to a lamp ballast to achieve reliable ignition within specifications of the related hardware. The operating state of the lamp is sensed to facilitate application of the power during lamp ignition.

Abstract: The present invention describes a method and circuitry for igniting high frequency operated, high intensity discharge lamps by means of a dual resonant circuit driven by a nonsinusoidal waveform; typically a square wave in the preferred embodiment. A capacitor in series with the lamp is selected to resonate at the fundamental frequency of the applied waveform when the lamp is in the on condition, providing thereby the high frequency power to the lamp for its normal operation. A capacitor in parallel with the lamp is chosen to resonate at a higher harmonic of the applied frequency, typically the third harmonic, when the lamp is in the off condition. Hysteresis heating causes the ignition voltage of the lamp to decrease as higher frequency power is applied, leading to ignition of the lamp at the third harmonic without applying to the lamp one or more pulses of high voltage.

Abstract: The present invention utilizes the natural damping of acoustic compression waves within an gas discharge tube, typically a high intensity discharge ("HID") lamp, to avoid resonant acoustic waves having sufficient amplitude to affect adversely the performance or lifetime of the HID lamp. The energy delivered to the HID lamp during each half-cycle of driving power is measured and adjusted such that the total time-averaged power delivered to the lamp remains constant at the lamp's rated power level, but the energy delivered to the discharge gas during each half-cycle is maintained below that level of half-cycle energy delivery at which acoustic resonance will overcome damping and build to harmful levels of amplitude. This is accomplished according to the present invention by varying the frequency of the applied electrical power. For a constant time-averaged power delivered to the lamp, increasing the frequency necessarily entails a reduction in the energy delivered per cycle.

Abstract: A high frequency electronic ballast (128) having a transformer (104) in which the transformer (104) has a primary winding (106) which is coupled to a secondary winding (108) via a primary flux path (1) from which flux can be diverted by a secondary flux path (2) including an air gap (114) which can be adjustable. Use of the transformer (104) permits load operation from a rectified alternating current power source which can be compensated by a high frequency power supply (192) to present a favorable power factor to the alternating current supply.