LED Input Voltage Control via Headroom Feedback
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Solution Overview
Problem
Current methods for controlling input voltage to LEDs in strobe applications are inefficient due to the application of overdrive voltage, which results in wasted energy as heat, as they fail to accurately account for varying forward voltage across LEDs over time.
Innovation Solution
A system comprising an energy storage device, current regulator, and control circuit that measures and adjusts the input voltage based on headroom voltage to minimize excess energy dissipation, ensuring the input voltage is only slightly above the total forward voltage of the LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If overdrive voltage is applied to ensure sufficient input voltage for LED activation, then reliability of LED activation is improved, but energy efficiency deteriorates due to excessive headroom voltage and heat dissipation
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors the forward voltage of LEDs and adjusts the input voltage accordingly. The control circuit receives feedback about actual LED voltage requirements and dynamically modifies the power supply output to maintain optimal headroom voltage, preventing both overdrive (energy waste) and underdrive (activation failure).
Solution Approach 2:
The system transitions from a static overdrive voltage approach to a dynamic voltage adjustment system. The input voltage is continuously adapted based on real-time LED forward voltage measurements, temperature conditions, and aging characteristics, allowing the system to maintain optimal efficiency while ensuring reliable activation under varying conditions.
2Adaptability or versatility
If fixed input voltage is applied to account for voltage variation across multiple LEDs, then adaptability to voltage variations is improved, but energy efficiency deteriorates due to excessive headroom voltage
Solution Approach 1:
The control circuit measures the actual forward voltage across the LED string and uses this feedback information to adjust the input voltage dynamically. This eliminates the need for fixed overdrive voltage while maintaining adaptability to voltage variations caused by LED manufacturing tolerances, temperature changes, and aging effects.
Solution Approach 2:
The system changes the input voltage parameter dynamically based on measured LED forward voltage characteristics. Rather than using a fixed conservative voltage level, the system continuously adjusts the voltage parameter to match actual LED requirements, reducing headroom voltage and improving energy efficiency while maintaining adaptability.
3Reliability
If higher input voltage is provided to ensure LED activation under worst-case conditions, then reliability is improved, but heat dissipation increases reducing system reliability
Solution Approach 1:
The system uses feedback from voltage sensing circuits to monitor actual LED forward voltage requirements and adjusts the power supply output accordingly. This prevents excessive voltage application that would generate unnecessary heat, while still ensuring sufficient voltage for reliable LED activation under all operating conditions.
Solution Approach 2:
The patent converts the potential harm of voltage variation and LED aging into a benefit by using these variations as feedback signals. The system measures actual LED voltage requirements and uses this information to optimize the input voltage, transforming what would be sources of inefficiency into opportunities for improved energy management and reduced heat dissipation.
Data Source
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AI summary
A method and apparatus for controlling an input voltage to a light emitting diode (LED) is disclosed. In one embodiment a system for controlling an input voltage to at least one LED includes an energy storage device. The energy storage device is coupled to the at least one LED. A current regulator is coupled the at least one LED for controlling activation and deactivation of the at least one LED. A control circuit is coupled to the current regulator for controlling a power supply providing an input voltage to the energy storage device, wherein the input voltage is provided in accordance with an amount of a headroom voltage measured across the current regulator.