MicroLED Power Control for High-Voltage Outlier Pixels
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Solution Overview
Problem
Existing LED driving techniques fail to address the issue of outlier pixels with abnormally high forward voltage (Vf), leading to undriven or underdriven LEDs that appear as dark spots, and result in increased heat losses or reduced electrical efficiency.
Innovation Solution
A control scheme that dynamically modulates the power supply voltage to accommodate outlier pixels by increasing it during specific PWM cycles, ensuring voltage compliance while minimizing heat losses and maintaining electrical efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power supply voltage is increased to accommodate outlier pixels with high forward voltage, then all pixels can be driven properly, but heat losses increase and electrical efficiency decreases
Solution Approach 1:
The power supply voltage is dynamically adjusted based on the operational status of LED pixels. During PWM dimming cycles, the voltage is increased to Vmax when driving outlier pixels with high forward voltage, and reduced to a lower level during off periods or when driving normal pixels. This dynamic voltage modulation ensures all pixels operate reliably while minimizing overall energy losses.
Solution Approach 2:
The patent implements periodic voltage modulation synchronized with PWM dimming cycles. The power supply voltage alternates between high (Vmax) and low levels in periodic fashion, matching the on/off cycles of LED pixels. This periodic action allows outlier pixels to receive sufficient voltage during their on-periods while reducing average power consumption and heat generation across the entire LED array.
2Reliability
If the power supply voltage is set to accommodate all pixels including outliers, then all pixels can operate, but electrical efficiency drops below acceptable levels
Solution Approach 1:
The power supply voltage is dynamically adjusted based on the operational status of LED pixels. During PWM dimming cycles, the voltage is increased to Vmax when driving outlier pixels with high forward voltage, and reduced to a lower level during off periods or when driving normal pixels. This dynamic voltage modulation ensures all pixels operate reliably while minimizing overall energy losses.
Solution Approach 2:
The patent changes the power supply voltage parameter dynamically rather than maintaining a fixed high voltage. By switching between high voltage (Vmax) during PWM on-periods for outlier pixels and lower voltage during off-periods or for normal pixels, the system achieves both reliable pixel operation and acceptable electrical efficiency (>85%).
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 effectively drives all pixels, including outliers, reducing the appearance of dark spots and minimizing heat losses, while maintaining electrical efficiency above 85%, thus providing a cost-effective and efficient driving solution for LED arrays.
Implementation Method 1
A control scheme that dynamically modulates the power supply voltage to accommodate outlier pixels by increasing it during specific PWM cycles
Implementation Method 2
If a forward voltage of a light emitting diode (LED) is above the supply voltage, the LED will likely not operate as expected
Data Source
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AI summary
A light-emitting apparatus can reduce a number of undriven or underdriven uLEDs in a uLED die. A method can include providing, by a power supply and during a first time, electrical power with a first voltage sufficient to operate a majority of micro light emitting diodes (uLEDs) of a uLED die to respective uLED drivers of the uLED die, driving the majority of uLEDs of the uLED die using the uLED drivers during the first time, providing, by the power supply and during a second time after the first time, electrical power with a second voltage, the second voltage higher than the first voltage and sufficient to operate uLEDs of the uLED die that are not operable by the first voltage, and driving the majority of the uLEDs and the uLEDs of the uLED die that are not operable by the first voltage during the second time.