METHOD AND SYSTEM FOR ENHANCED DIMMING RESOLUTION IN A LIGHT BALLAST THROUGH USE OF MULTIPLE CONTROL FREQUENCIES

摘要

A microcontroller or state machine controls a light ballast utilizing a timer structure. The microcontroller can program the timer structure to generate pulses where the "average" frequency of a series of pulses can be varied with higher resolution than the frequency of a single pulse. This variation can occur without further microcontroller/state machine intervention. The pulses are used to control the on and/or off time of the light. The timer can be configured to modulate the outputs fast enough to ensure that the light does not appear to flicker to the human eye by limiting the number of pulses in a frame and by increasing the number of times the frequency shift occurs compared to the obvious implementation. The present invention relies on the fact that the human eye is not capable of detecting small frequency changes in high frequency signals and therefore uses pulses of two or more frequencies where the frequencies are close together. The average frequency can then be varied at much higher resolution than any single frequency.