Dynamic PWM Dimming for Flicker-Free High-Power LED Control
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Solution Overview
Problem
Existing methods for controlling high-power LED lighting using PWM signals result in flickering during camera shots due to insufficient dimming smoothness and high refresh rates, leading to unsmooth dimming and camera flickering.
Innovation Solution
A method and system that dynamically adjust the PWM signal by dividing the duty ratio adjustment into two modes: one mode adjusts the signal period while keeping the effective pulse duration constant to prevent flickering, and the other mode adjusts the effective pulse duration while keeping the signal period constant to prevent unsmooth dimming, ensuring smooth dimming and preventing camera flickering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the refresh rate of the LED light is increased to prevent camera flickering during shooting, then camera flickering is reduced, but the dimming smoothness deteriorates due to hardware performance limitations
Solution Approach 1:
The patent applies dynamics by making the PWM signal parameters adjustable and adaptive. The system dynamically changes the pulse width and signal period based on operating conditions to optimize both camera flicker prevention and dimming smoothness. This is achieved through configurable pulse widths (1ms to 255ms) and adjustable signal periods that adapt to different brightness levels and camera exposure settings.
Solution Approach 2:
The patent implements parameter changes by modifying key PWM parameters including pulse width duration, signal period, and duty ratio. The system adjusts these parameters dynamically - increasing pulse width at lower brightness levels to maintain smoothness, and optimizing the signal period to synchronize with camera exposure frequencies, thereby preventing flicker while maintaining control precision.
2Speed
If the pulse width of the PWM signal is shortened to improve dimming response speed, then dimming response speed is improved, but the minimum dimming depth increases leading to loss of low brightness control
Solution Approach 1:
The patent applies dynamics by implementing variable pulse width modulation where the pulse width is not fixed but adapts based on the desired brightness level. The system uses a configurable pulse width range (1ms to 255ms) that dynamically adjusts to maintain adequate minimum dimming depth while preserving fast response characteristics when higher brightness is required.
Solution Approach 2:
The patent implements parameter changes by adjusting the pulse width parameter based on operating conditions. The system maintains a minimum pulse width of 1ms to ensure sufficient dimming depth control at low brightness levels, while allowing pulse width to extend up to 255ms when higher brightness and faster response are needed, thus optimizing both response speed and minimum dimming depth.
Data Source
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AI summary
The present invention provides a method and a system for dynamically adjusting a PWM signal, and a system for dynamically controlling a high-power light. The method includes steps of: presetting a standard signal period and a standard duty ratio of an effective pulse; receiving a target duty ratio entered by a user and comparing the target duty ratio with the standard duty ratio; adjusting a duration of a signal period relative to the standard signal period while keeping a duration of the effective pulse unchanged to cause a duty ratio to reach the target duty ratio, and generating a corrected PWM signal according to the adjusted duration of the signal period and the target duty ratio, when the target duty ratio is smaller than the standard duty ratio; adjusting the duration of the effective pulse while keeping the duration of the standard signal period unchanged to cause the duty ratio to reach the target duty ratio, and generating a corrected PWM signal according to a duration of the standard signal period and the target duty ratio, when the target duty ratio is larger than the standard duty ratio; and generating a corrected PWM signal according to the standard duty ratio and the duration of the standard signal period when the target duty ratio is equal to the standard duty ratio. The method is capable of preventing flickering in the shooting of a camera or unsmooth dimming when adjusting the duty ratio.