LED illumination light modulation method controlling both voltage and duty ratio

Abstract

The invention belongs to the LED illumination technology, and particularly relates to an LED illumination light modulation method controlling both voltage and duty ratio. The hardware of the method comprises an adjustable voltage source, a current limiting resistor, an LED light source, an electronic switch and a pulse signal source. According to the invention, light modulation is performed on an LED by adopting the method for changing the working voltage and the driving duty ratio of the LED; under the condition that the pulse resolution ratio is kept unchanged, and under the different brightness adjusting requirements, light modulation voltage of the LED is adjusted according to different shifts; under the low brightness requirement, the working voltage of the LED is reduced; and under the high brightness requirement, the working voltage of the LED is increased. Under each shift, the dynamic range of pulse width light modulation is kept unchanged, so for each additionally arranged voltage shift, the dynamic range of the light modulation is relatively doubled. The light modulation voltage is only based on the shift without being adjusted to the quite low voltage, and the resolution ratio of the pulse is unchanged, so the big dynamic requirement for the brightness adjustment can be considered, cost can be reduced and conversion efficiency and reliability are improved.

Description

technical field [0001] The invention relates to the field of LED lighting dimming, in particular to an LED lighting dimming method with double control of voltage and duty cycle. Background technique [0002] At present, due to the popularity of dimming technology, various terminals with display screens, mobile phones, PDAs, computers, monitors, TVs, and even lighting equipment such as car dashboards and aircraft cockpit instruments have brightness adjustment functions. LED light sources have been widely used in this type of lighting equipment, and the LED light sources need to be dimmed. [0003] Traditionally, there are two methods of LED dimming: one method is to change its working voltage for dimming, this method needs to design an adjustable voltage source, the circuit is complex, the cost is high, and when the brightness is low, the circuit loss large; and the linearity of the brightness and voltage of the LED is very poor at low brightness, and a high price is require...

AI Technical Summary

Problems solved by technology

If the duty cycle adjustment is simply used, in order to improve the dynamic range of the control, the pulse resolution must be improved. However, when the pulse resolution is improved, the pulse width is very narrow at low duty cycle. Due to the parasitic inductance of the line, the line, switch The influence of distributed capacitance on components, LED light sources and other circuits forms an integral effect, and the phenomenon of duty cycle loss will occur. When the duty cycle is adjusted to the low end, the LED brightness cannot be adjusted, or brightness jitter occurs, causing The LED dimming effect is very poor at low brightness, and the adjustment of very low brightness cannot be realized

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