| 摘要 |
Perceived intensity (brightness) of light from a light emitting diode (LED) is controlled with a pulse train signal having fixed pulse width and voltage amplitude and then increasing or decreasing the frequency (increasing or decreasing the number of pulses over a time period) of this pulse train signal so as to vary the average current through the LED. This reduces the level of electro-magnetic interference (EMI) at any one frequency by varying the pulse train energy spectrum over a plurality of frequencies. |
