Light controller connected to piezoelectric transformer for controlling cold cathode tube by changing frequency or duty factor depending upon luminous intensity

摘要

A piezoelectric transformer drives a cold cathode tube under the control of a light controller; when the cold cathode tube is radiating in a small luminous intensity range, the light controller changes the duty factor of a driving signal supplied to the piezoelectric transformer so as to adjust the cold cathode tube at a target luminous intensity, and prevents the cold cathode tube from undesirable luminous gradient; when the cold cathode tube is radiating in a large luminous intensity range, the light controller changes the frequency of the driving signal so as to adjust the cold cathode tube to a target luminous intensity, and prevents a power supply unit from undesirable frequent load variation.