PWMabbr. Pulse Width Modulation (PWMabbr) adopts the method of adjusting voltage, current and power by adjusting Pulse proportion. It can be easily controlled by single chip microcontroller, which can easily be controlled by single chip microcomputer. The use of certain elements can be used to raise or drop pressure, convenient to use direct current, also can obtain sinusoidal alternating current through PWM. It can be conveniently closed loop adjustment
I think it might be the adjustment of light intensity by the amount of time that is broken in the unit time
LED's dimming control has traditionally been done by using a DC signal or filter PWM to adjust the forward current in the LED. Reduce the LED current will rise to adjust the intensity of the LED light output, however, the change of the forward current will also change the LED color, because the shade of the LED will change as the change of electric current. Many applications (such as car and LCD TV backlighting) cannot allow any colour drift in leds. In these applications, due to the light are different in the surrounding environment changes, and human eyes are sensitive to Yu Guangjiang tiny change, so wide range of light is required. By applying a PWM signal to control the LED brightness, the leds are tuned without changing color.
It's a kind of modulation Generally speaking, the dimming mode has dc voltage dimming, built-in Burst mode dimming and external PWM dimming. The PWM adjustment is divided into positive and negative light, which is when the ratio is 100%, and the negative light is the lightest. Take the positive light When PWM is high current, glow; Low level is, don't shine. Because the frequency is so fast, we don't feel the indirect glow. In this way, the brightness can be adjusted by adjusting the PWM's air ratio You can do a good contrast.
