ELECTRONIC CIRCUIT FOR OPERATING HID LAMP AND IMAGE PROJECTOR

摘要

PROBLEM TO BE SOLVED: To develop an electronic circuit for operating an HID lamp capable of controlling the luminance through the lamp life and using a sensor of an easier structure and thus an inexpensive sensor, and an image projector comprising such an electronic circuit. SOLUTION: This electronic circuit comprises a lamp ballast for supplying a controlled lamp current for operating the HID lamp according to a control signal, and a luminance sensor for generating and supplying a sensor signal, the sensor signal representing the light quantity emitted in the position of the luminance sensor by the HID lamp. This circuit further comprises a filter constituted as a high-pass filter for supplying the control signal by the high-pass filter processing of the sensor signal.