DYNAMIC REACTORLESS HIGH-FREQUENCY VAPOR LAMP BALLAST

摘要

A control device and method of operation for a discharge lamp which would under normal operation display a runaway discharge characteristic. The control device constitutes a part of a low-impedance power supply which is without any effective current limiting impedance, and is thus a high-efficiency device. A high-frequency discharge sustaining potential is applied across the discharge lamp at a repetition rate of at least about 500 times per second. A feedback control signal is generated based on a predetermined lamp operating condition, and this feedback signal is used to control the duty cycle of operation, with each period of potential application not exceeding about 1.8 milliseconds, and with the duty cycle always being less than unity. The repetition rate of potential application may be simultaneously varied with the duty cycle of a feedback signal so that a particular discharge lamp operates at an optimum repetition rate.