LED Driving Control With Variable PWM Frequency for Flicker-Free Dimming
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Solution Overview
Problem
Existing lighting systems exhibit camera flicker issues and inadequate dimming performance, failing to meet flicker standards and achieving optimal dimming quality.
Innovation Solution
A driving system for lighting apparatuses that utilizes a controller to provide digital control signals with adjustable frequencies and duty cycles to manage the brightness and color temperature of multiple light sources, incorporating a power converter and switching arrangement to overcome these issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed frequency PWM signal is used to control LED brightness, then the control system is simple, but camera flicker occurs and flicker standards are not met
Solution Approach 1:
The patent applies dynamics by making the PWM frequency adjustable rather than fixed. The controller can dynamically change the frequency of the PWM signal based on operating conditions, allowing the system to avoid frequencies that cause camera flicker while maintaining simplicity in the overall control architecture.
Solution Approach 2:
The patent changes the frequency parameter of the PWM signal from a fixed value to a variable parameter. By adjusting the frequency parameter within a specific range (e.g., 20kHz to 100kHz), the system can eliminate camera flicker effects while maintaining effective LED dimming control.
2Object-affected harmful factors
If the PWM frequency is increased to reduce camera flicker, then camera flicker is reduced, but dimming performance deteriorates
Solution Approach 1:
The system dynamically adjusts between frequency and duty cycle parameters based on operating conditions. When high frequency is needed to reduce flicker, the system compensates by optimizing duty cycle values to maintain dimming precision. This dynamic parameter adjustment resolves the trade-off between flicker reduction and dimming performance.
Solution Approach 2:
The patent optimizes the relationship between frequency and duty cycle parameters. By carefully selecting frequency values and corresponding duty cycle ranges, the system achieves both flicker reduction and maintained dimming performance through coordinated parameter changes rather than independent adjustments.
3Manufacturing precision
If the PWM frequency is decreased to improve dimming performance, then dimming performance is improved, but camera flicker increases
Solution Approach 1:
The controller dynamically selects the appropriate PWM frequency based on the desired dimming level and operating conditions. For applications requiring precise dimming control, the system can operate at lower frequencies, while for applications sensitive to flicker, it automatically transitions to higher frequencies, providing adaptive optimization of both parameters.
Data Source
AI summary
A driving system for a lighting apparatus comprising a plurality of light sources, the driving system comprising a controller configured to provide a first digital control signal to the lighting apparatus, the first digital control signal having a first duty cycle and a first frequency, and control the first frequency of the first digital control signal.