LED Driver Voltage Control for Power Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Linear current sources used for driving light emitting diodes (LEDs) have limited power efficiency due to voltage variations caused by temperature dependence, spread, and aging, leading to excessive power dissipation and increased costs.
Innovation Solution
An electronic device with a control mechanism that adjusts the switch-mode power supply based on the voltage across the current source to maintain a minimum voltage necessary for operation, reducing excess voltage and power losses by dynamically controlling the supply voltage in response to sensed voltage variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed voltage supply is used for driving LED strings, then the current sources can maintain constant current through LEDs, but the voltage across current sources becomes large causing excessive power dissipation and heat generation
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed voltage supply to a dynamic voltage supply that adjusts in real-time. The controlling means continuously monitors the voltage across the current source and dynamically adjusts the switch-mode power supply output voltage to maintain only the minimum necessary voltage, thereby reducing power dissipation while ensuring reliable constant current operation.
Solution Approach 2:
The patent implements feedback control where the controlling means senses the voltage across the current source and uses this information to adjust the power supply output. This closed-loop feedback mechanism ensures that the voltage is maintained at the minimum level required for proper current source operation, preventing excessive voltage and power loss.
2Measurement precision
If linear current sources are used to drive LEDs, then accurate current control and fast switching are achieved, but power efficiency is limited due to voltage variations from temperature, spread, and aging
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the power supply voltage parameter based on actual operating conditions. Instead of using a fixed high voltage that accommodates worst-case scenarios, the system continuously adapts the voltage parameter to match the actual LED string characteristics, thereby improving power efficiency while maintaining accurate current control.
Solution Approach 2:
The system transitions from static linear current sources to a dynamic switch-mode power supply controlled by real-time voltage sensing. This dynamic approach allows the system to respond to temperature variations, aging, and manufacturing spread, maintaining current accuracy while significantly improving power efficiency compared to fixed voltage supplies.
3Reliability
If higher supply voltage is used to accommodate LED voltage variations, then all LEDs in the string can be driven reliably, but the voltage drop across current sources increases producing more heat
Solution Approach 1:
The controlling means uses feedback from voltage sensing across the current source to adjust the power supply output. This ensures that the supply voltage is reduced to the minimum level required for reliable LED operation, thereby minimizing the voltage drop across current sources and reducing heat dissipation while maintaining operational reliability.
Solution Approach 2:
Instead of applying excessive voltage to all LEDs to ensure worst-case reliability, the system applies just enough voltage (partial action) by continuously sensing and adjusting. This approach achieves reliable operation without the excessive voltage headroom that causes unnecessary power loss and heat generation in the current sources.
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
This approach reduces power consumption and heat dissipation by ensuring the voltage across the current source is minimized, improving the efficiency and cost-effectiveness of LED driving systems while maintaining proper operation.
Implementation Method 1
an electronic device for driving a light emitting semiconductor device
Data Source
AI summary
The present invention relates to an electronic device for driving a light emitting semiconductor device, which includes controlling means (CNTL) being adapted for controlling a switch mode power supply for supplying the light emitting semiconductor device in response to a sensing value received by the controlling means which is indicative of a voltage across a current source for determining a current through the light emitting semiconductor device, wherein the switch-mode power supply is controlled such that the voltage across the current source is minimum.