LED Dithering Control for Smooth Dimming

The patent applies periodic action by using pulse width modulation (PWM) to switch the LED on and off at high frequencies. Instead of continuously varying current, the system uses periodic switching with duty cycles adjusted to control average light output. This periodic switching approach, combined with dithering between multiple frequency bands, maintains smooth dimming while avoiding perceptible flicker by keeping switching frequencies above human visual detection thresholds.

The patent implements dynamics by dithering between multiple variable frequency bands rather than using a single fixed frequency. The system dynamically adjusts the operating frequency within bands and transitions between bands to maintain optimal performance across different dimming levels. This dynamic frequency adjustment prevents the system from operating at problematic fixed points that could cause flicker or perceptible intensity jumps.

The patent applies parameter changes by dithering between multiple frequency bands with distinct on-times and variable periods. Instead of making abrupt transitions between intensity levels, the system changes multiple parameters simultaneously (frequency, duty cycle, on-time) across different bands. This multi-parameter approach allows smooth transitions that are imperceptible to the human eye while maintaining ease of dimming control through digital signal processing.

The patent uses digital filtering as an intermediary between the control signal and the LED driving waveform. The digital filter processes the dimming command and generates smoothed transition waveforms that prevent abrupt intensity changes. This intermediary processing stage transforms simple dimming commands into complex, smooth waveform transitions that eliminate perceptible flicker while maintaining ease of operation.

The patent implements feedback by continuously monitoring the actual light output and comparing it with the desired intensity level. The system uses this feedback information to adjust the dithering parameters and frequency band selections in real-time, compensating for deviations in average current. This closed-loop control ensures precise light intensity maintenance across the full dynamic range while expanding the controllable intensity spectrum through variable frequency operation.

The patent extracts and separates the dimming control into distinct frequency bands with specific characteristics. By dividing the overall frequency range into multiple bands, each optimized for specific intensity ranges, the system can precisely control light output in each band independently. This extraction approach allows the system to achieve wide dynamic range while maintaining precision by selecting appropriate bands for each dimming level rather than relying on a single variable frequency control mechanism.