LED Dimming System Equivalent Current Regulation
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Solution Overview
Problem
Current LED dimming methods, such as PWM, suffer from reduced dimming uniformity and noise generation due to mechanical vibrations caused by inductor coils, which affect the stability and luminosity of LCDs.
Innovation Solution
A method and system that calculates the equivalent current based on the duty cycle of the PWM signal and regulates the LED current to match this equivalent current, improving dimming uniformity and eliminating noise by ensuring current flows consistently throughout the dimming cycle without altering the duty cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If PWM dimming is used to regulate LED current, then dimming capability is achieved, but dimming uniformity deteriorates due to fixed delay consumption
Solution Approach 1:
The patent changes the control parameter from duty cycle to equivalent current. Instead of using PWM duty cycle to control LED brightness, the system calculates the equivalent current based on the duty cycle message and directly regulates the LED current to match this equivalent value. This parameter transformation eliminates the fixed delay issue and achieves linear dimming uniformity across the entire dimming range.
2Ease of operation
If low frequency switching signal is used in PWM dimming, then dimming control is achieved, but harmful noise is generated due to inductor coil vibrations
Solution Approach 1:
The patent replaces the mechanical PWM switching system with an equivalent current regulation system. Instead of using high-frequency switching signals that cause inductor vibrations and audible noise, the system calculates the equivalent current representation of the desired dimming level and directly controls the LED current to match this equivalent value. This substitution eliminates the mechanical vibration source while preserving the dimming control function.
3Ease of operation
If PWM duty cycle is varied to control LED power, then dimming function is achieved, but dimming uniformity deteriorates due to non-linear relationship between duty cycle and perceived brightness
Solution Approach 1:
The patent transforms the control parameter from duty cycle (which has a non-linear relationship with perceived brightness) to equivalent current (which has a linear relationship with perceived brightness). By calculating the equivalent current based on the duty cycle message and directly regulating the LED current to match this equivalent value, the system achieves linear and uniform dimming perception across the entire brightness range.
Data Source
AI summary
The present invention discloses a LED dimming method and a LED dimming system, wherein the LED dimming method comprises the following steps: A: calculating the equivalent current flowing through the LED in accordance with the duty cycle message of the input PWM signal; and B: regulating the current flowing through the LED to the equivalent current. Because the equivalent current flowing through the LED is calculated by the duty cycle message D of the input PWM signal while the duty cycle is not actually regulated, the present invention realizes the aim that the dimming uniformity is improved by linearly regulating the current flowing through the LED. Meanwhile, transformer noise will not be generated because current flows through the transformer in the overall dimming cycle.