| 摘要 |
<p>An LED driver circuit sequentially and repeatingly switches a plurality of LED arrays to result in blink with high frequency. A PWM generator outputs n series of high frequency periodic PWM signals. The period (T) and duty cycle (d) of each series of PWM signal are the same as each other, but pulse portions of the PWM signals sequentially follow over time, i.e. d=1/n. Each PWM signal is sent to a dimming constant current source for separately outputting a driving power with the same timing as the input PWM signals to one of the LED arrays, so that the LED arrays make a high frequency blink. The blink frequencies of each and overall LED arrays are 1/T Hz and n/T Hz, respectively. The driving current of LEDs can be increased over a rated average forward current I AVG because they are not lit up continuously. By persistence of vision of the eye, a visual effect with continuity and high brightness can be obtained.</p> |
