LED Driving Device Pulse Density Control for Linearity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional PWM driving methods experience linearity issues and transient problems, especially at higher frequencies and lower duty ratios, affecting the driving characteristics of LED loads.
Innovation Solution
An LED driving device comprising a control module and a driving module that calculates pulse intensity, second pulse width, and pulse density based on the driving characteristic and load energy of the LED load, generating a driving signal to improve linearity and reduce transient impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If PWM frequency is increased, then the response speed of the driving signal is improved, but the linearity of the driving signal deteriorates and transient problems become more obvious
Solution Approach 1:
The patent segments the PWM driving signal into multiple pulse widths within a frame time, calculating different pulse widths based on the driving characteristic and load energy. This segmentation allows the system to maintain linearity by distributing the total pulse duration across multiple smaller pulses, reducing the transient impact of each individual pulse while maintaining the overall response speed through high-frequency PWM operation.
Solution Approach 2:
The patent dynamically adjusts the pulse width based on the driving characteristic and load energy of the LED load. By making the pulse width variable rather than fixed, the system can adapt to different operating conditions and maintain optimal linearity across varying duty ratios and frequencies, resolving the contradiction between response speed and linearity.
2Speed
If PWM frequency is increased, then the response speed of the driving signal is improved, but the transient problem becomes more obvious especially at lower duty ratio
Solution Approach 1:
The patent calculates and determines the optimal pulse width in advance based on the driving characteristic and load energy before generating the driving signal. This preliminary calculation allows the system to prepare the driving signal with appropriate pulse parameters that minimize transient effects, ensuring reliable operation even at high frequencies and low duty ratios where transient problems would otherwise be most pronounced.
Solution Approach 2:
The patent changes the pulse width parameter dynamically based on the driving characteristic and load energy. By adjusting this key parameter, the system can maintain the pulse width within optimal ranges that reduce transient effects, allowing high-frequency PWM operation without the transient problems that would normally occur at low duty ratios.
3Loss of energy
If duty ratio is decreased, then the power consumption is reduced, but the peak value of the driving signal decreases affecting the driving characteristics
Solution Approach 1:
The patent segments the total pulse width into multiple smaller pulses within the frame time. This segmentation allows the system to achieve the desired low duty ratio for reduced power consumption while maintaining sufficient peak values in each individual pulse to preserve driving characteristics. The cumulative effect of multiple smaller pulses achieves the target duty cycle without compromising the effectiveness of each pulse.
Solution Approach 2:
The patent applies partial action by using multiple smaller pulses instead of a single long pulse. Each individual pulse has a reduced width (partial action) that maintains adequate peak values, while the collection of multiple pulses achieves the overall low duty ratio for reduced power consumption. This approach balances the competing requirements of low power consumption and maintained driving characteristics.
Data Source
AI summary
An LED driving device includes an LED load, a control module and a driving module. The LED load has a driving characteristic and a load energy. The control module provides a frame time and a first pulse width to calculate a total pulse number in the frame time. The control module generates a pulse intensity and a second pulse width according to the driving characteristic of the LED load. The control module generates a pulse density according to the load energy of the LED load. The driving module generates a driving signal to the LED load according to the pulse intensity, the second pulse width and the pulse density.