SYNCHRONOUS OPERATION SYSTEM FOR DISCHARGE TUBE LIGHTING DEVICE, DISCHARGE TUBE LIGHTING DEVICE, AND SEMICONDUCTOR INTEGRATED CIRCUIT

摘要

Each discharge tube lighting device comprises a saw-tooth wave oscillator for generating a saw-tooth signal, by which a plurality of switching elements for feeding an electric current to the primary winding of a transformer in a resonance circuit connected with a discharge tube and to a condenser are subjected to a PWM control, a PWM comparator for controlling the switching elements on the basis of the saw-tooth signal, and a pulse synchronizing circuit for synchronizing the oscillation frequency of the saw-tooth signal with the frequency of a synchronous pulse signal from a common line when the synchronous pulse signal based on a pulse signal for transmitting the frequency information of the saw-tooth signal is outputted to the common line and the synchronous pulse signal is inputted from the common line. The synchronous pulse signal is mutually transmitted and received between one or more discharge tube lighting devices through the common line, and a voltage uniformed in frequency and phase is applied to one end of each of the one or more discharge tubes.