Abstract: A mercury vapor electric discharge lamp is supplied with AC electric power, which is variable over a wide range, to control the lamp output power in the form of the intensity of the electromagnetic radiation emitted over a correspondingly wide range of from approximately 5% to 100% or better of rated output power without lamp extinction. An AC phase modulation control circuit controls the AC electric power supplied to the lamp such that applied voltage remains relatively constant while the current is controllably varied determined by the phase angle of conduction in the control circuit. Control of the AC phase modulation control circuit is effected in response to the actual output power of the electromagnetic radiation emitted by the lamp, the speed of a printing press or conveyor line with which the lamp may be used to cure ultraviolet sensitive inks, paints, plastics and the like on some form of substrate.

Abstract: An improved photocontrol system for electrical lamps comprising the combination of photoelectric means responsive to the intensity of the ambient light for controlling the turning the lamps on and off, and an electronic timer for turning off the lamps at a preset time interval, after they have been turned on.