Controlled lighting device

摘要

A lighting device in which an amount of light emitted by a lamp is detected by a light receiving element for controlling the input voltage of the lamp commensurate with the detected amount of light. By utilizing a pre-illumination system in conjunction with the lighting device, it is possible to improve the sensitivity characteristics of the light receiving element as the lamp is being charged up to a desired level of illuminescence and to prevent the input of an excessive voltage to the lamp.