Method for coloring mixing of hid lamps operated at VHF frequencies using duty cycle modulation

摘要

A method of color mixing a very high frequency operated HID lamp which effectuates power modulation to the HID lamp at a frequency of the second longitudinal acoustic mode by modulating the duty cycle of a half bridge configured resonant inverter. The duty cycle is modulated with a modulation frequency which is substantially one-half the frequency of the second longitudinal acoustic mode of the HID lamp. In operation, exciting the second longitudinal acoustic mode of the HID lamp with the half bridge configured resonant inverter operated with a modulated duty cycle achieves color mixing along a vertical axis of the HID lamp.