LED Driver Circuit Beyond Nominal Luminance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing LED array control systems limit the luminance of stronger LEDs to prevent overheating, resulting in inefficient use of resources and reduced brightness and contrast due to uniform design based on the weakest LED's nominal luminance.
Innovation Solution
A circuit that generates a pulse-width modulated drive signal and uses forward voltage sensing to control current delivery, allowing LEDs to operate beyond nominal luminance while maintaining junction temperatures within a safe range, thereby stabilizing flux and enabling higher luminance and contrast without degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the LED array is designed to guarantee nominal luminance of the weakest LED, then reliability is improved, but luminance output and contrast are reduced
Solution Approach 1:
The patent implements individual LED monitoring and control, where each LED's forward voltage is measured and its current is independently adjusted. This allows each LED to operate at its optimal luminance level based on its specific characteristics rather than being constrained by the weakest LED, thereby improving overall luminance output while maintaining reliability through individualized protection.
Solution Approach 2:
The system dynamically adjusts LED operating parameters by continuously monitoring forward voltage and modifying drive current in real-time. This dynamic control enables the LED array to adapt to varying conditions and individual LED characteristics, allowing stronger LEDs to operate beyond nominal luminance while preventing overheating through active current regulation.
2Temperature
If PWM control is used to limit power delivery to the LED array, then temperature control is improved, but luminance capability is reduced
Solution Approach 1:
The patent employs feedback control by measuring the forward voltage of each LED and using this information to regulate the drive current. This feedback mechanism enables precise temperature control through current adjustment while maintaining higher luminance capability, as the system responds to actual LED conditions rather than using fixed PWM dimming limits.
Solution Approach 2:
The system changes the operating parameters of individual LEDs based on their forward voltage measurements. By adjusting drive current according to measured forward voltage, the system optimizes both temperature control and luminance output for each LED, allowing stronger LEDs to operate at higher luminance levels without excessive temperature increase.
3Illumination intensity
If individual LED monitoring and current adjustment is implemented, then luminance optimization is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple functions into integrated control circuitry that performs forward voltage measurement, current regulation, and temperature protection simultaneously. By merging these functions into a unified system rather than separate components, the patent reduces overall device complexity while achieving individual LED optimization through shared measurement and control infrastructure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables individual LEDs to be driven beyond their nominal luminance, achieving higher luminance and contrast while preventing overheating, thus optimizing the performance of LED arrays by utilizing the capabilities of more capable LEDs.
Implementation Method 1
light-emitting diodes (LEDs) that make up an LED array
Implementation Method 2
The individual light-emitting diodes (LEDs) that make up an LED array
Implementation Method 3
The LED junction temperature can be measured more efficiently when using a forward voltage measurement and the known relationship between the forward voltage and temperature
Data Source
AI summary
Various embodiments relate to an light-emitting diode (LED) driver and related method that drives various LEDs in an LED string beyond their isolated nominal luminance. Individual LEDs in an LED string may be thermally dependent so that specific LEDs may operate at higher temperatures without degradation. This may include driving specific LEDs beyond isolated nominal luminance when associated LEDs dim below their isolated nominal luminance. Such operation allows the LED to receive higher amounts of current and therefore exhibit higher luminous intensity. A control circuit may monitor the forward voltage and temperature in a feedback loop to ensure that the LEDs in the string are operating below a defined maximum junction temperature. The control circuit may signal a processing unit to adjust adjacent circuits to compensate when the controlled LEDs cannot produce a requested luminance without operating beyond a maximum junction temperature.