DISCHARGE LAMP LIGHTING APPARATUS, AND IMAGE DISPLAY APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting apparatus using a switching circuit controlled by a microcomputer, in which a smoothing circuit for converting an output pulse signal from the microcomputer into a DC voltage Vth as a control command has high smoothness of the converted DC voltage without increasing the time constant of the smoothing circuit; and the apparatus can respond to rapid change of the loading state. SOLUTION: The discharge lamp lighting apparatus comprises a detection circuit for detecting the lighting state of a discharge lamp; a microcomputer for calculating an output value according to the detected value for every predetermined period and outputting it as a pulse signal; a smoothing circuit for converting the pulse signal outputted from the microcomputer into a DC voltage according to its effective value; and a signal producing circuit for controlling an on-period of a switching element of a power conversion circuit according to the level of the DC voltage outputted from the smoothing circuit, wherein the pulse signal outputted from the microcomputer within the predetermined period consists of a plurality of pulses having fixed width tmin outputted at almost equal intervals. COPYRIGHT: (C)2008,JPO&INPIT