LED Driver Voltage Optimization via Lowest Voltage Detection
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Solution Overview
Problem
In liquid-crystal display (LCD) panels, the error in forward voltage of LEDs leads to voltage drop issues in light-emitting portions, resulting in inadequate light emission or excessive heat generation, which existing LED drivers struggle to optimize effectively.
Innovation Solution
A light-emitting device driving apparatus with multiple channels, including a lowest voltage detection circuit, sample hold circuit, and feedback control circuit, which adjusts the light emission driving voltage by comparing voltages across channels and providing feedback to the power supply to maintain optimal voltage levels, thereby controlling light emission and reducing heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the output voltage of the power supply device is increased to compensate for LED forward voltage errors, then sufficient voltage is provided to all light-emitting portions, but excessive heat is generated
Solution Approach 1:
The light-emitting portions are divided into multiple channels, with each channel independently controlled by its own driver block. The power supply device provides separate voltage outputs for each channel, allowing targeted voltage compensation only where needed rather than uniformly increasing voltage across all channels.
Solution Approach 2:
Each channel receives a customized voltage level tailored to its specific LED forward voltage characteristics. The feedback control circuit adjusts the output voltage of each channel independently based on detected voltage drops, ensuring each light-emitting portion receives exactly the voltage it needs without excess.
2Object-generated harmful factors
If feedback control is implemented to optimize output voltage, then heat generation is reduced, but the system complexity increases
Solution Approach 1:
The feedback control system automatically monitors and adjusts output voltages without external intervention. The lowest voltage detection circuit continuously monitors channel voltages and provides feedback signals that trigger automatic voltage adjustments, eliminating the need for manual calibration or external control.
Solution Approach 2:
A feedback control circuit receives voltage information from the lowest voltage detection circuit and automatically adjusts the power supply device output. When the detected voltage drops below a threshold, the feedback circuit generates control signals to increase the output voltage, creating a self-regulating system that maintains optimal operating conditions.
3Object-generated harmful factors
If the output voltage is set too low to minimize heat, then insufficient voltage reaches some light-emitting portions, but heat generation is reduced
Solution Approach 1:
The output voltage of each channel is dynamically adjusted based on real-time detection of voltage drops. Rather than using a fixed voltage setting, the system continuously adapts voltage levels to match actual LED requirements, ensuring sufficient voltage delivery while minimizing excess heat generation.
Solution Approach 2:
The system changes the output voltage parameter of each channel based on detected conditions. When voltage drop exceeds a threshold, the feedback control circuit modifies the voltage parameter to an appropriate higher level, ensuring reliable operation without maintaining excessively high voltage that would cause unnecessary heat.
Data Source
AI summary
An object of the present invention is to optimize a light-emitting driving voltage for each light-emitting portion.A light-emitting diode (LED) driver (10A) includes: driver blocks (20) of a plurality of channels, each driver block (20) having a light-emitting portion connecting terminal (CH) to be connected to a light-emitting portion (LL) including one or more than one LED, the light-emitting portion being caused to emit light by a current flowing through the light-emitting portion connecting terminal to the light-emitting portion; a lowest voltage detection circuit (40), detecting and outputting a lowest voltage among voltages of the light-emitting portion connecting terminals of each channel; a sample hold circuit (50), comparing an output voltage (VLS) of the lowest voltage detection circuit with a hold voltage (VLS_SH) thereof, and updating the hold voltage to the output voltage if the output voltage is lower than the hold voltage; and a feedback control circuit (60), outputting a feedback signal according to the hold voltage and a predetermined reference voltage to a power supply device (11) providing a light emission driving voltage (Vo) to the light-emitting portions of the plurality of channels, so as to control the light emission driving voltage.