Micro-LED Drive Voltage Compensation for Luminance Uniformity
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Solution Overview
Problem
Display devices using micro-LEDs with different areas face challenges in maintaining long-term reliability due to differences in chromaticity and lifetime, as optimal quantum efficiency depends on the LED size, leading to variations in luminance and current density.
Innovation Solution
The display device employs a configuration with multiple sub-pixels, each containing micro-LEDs of different areas, where specific drive voltages are applied based on the optimal quantum efficiency to ensure uniform luminance and minimize chromaticity differences, using equations to calculate luminous intensity based on chip area and luminance, and optimizing chip area for optimal quantum efficiency and current density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If micro-LEDs with different areas are used in sub-pixels, then area gradation can be achieved for display, but differences in chromaticity and lifetime occur due to varying quantum efficiency
Solution Approach 1:
The patent applies local quality by providing different drive voltages to micro-LEDs of different areas. Specifically, a first drive voltage is applied to a first micro-LED with a first area, and a second drive voltage is applied to a second micro-LED with a second area. This localized adjustment of electrical parameters compensates for the area-dependent quantum efficiency variations, ensuring that micro-LEDs across different sizes achieve uniform luminance and chromaticity, thereby resolving the reliability issue while maintaining area gradation capability
Solution Approach 2:
The patent changes the drive voltage parameter based on micro-LED area to optimize performance. By calculating and applying area-specific drive voltages, the system compensates for the non-linear relationship between LED area, current density, and quantum efficiency. This parameter adjustment ensures that smaller micro-LEDs (which have lower optimal current density) and larger micro-LEDs (which have higher optimal current density) both operate at their peak quantum efficiency, minimizing chromaticity differences and extending lifetime
2Illumination intensity
If micro-LEDs of different areas are used, then luminance control is possible, but variations in current density affect quantum efficiency and luminance uniformity
Solution Approach 1:
The patent changes the drive voltage parameter based on micro-LED area to optimize performance. By calculating and applying area-specific drive voltages, the system compensates for the non-linear relationship between LED area, current density, and quantum efficiency. This parameter adjustment ensures that smaller micro-LEDs (which have lower optimal current density) and larger micro-LEDs (which have higher optimal current density) both operate at their peak quantum efficiency, minimizing chromaticity differences and extending lifetime
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 mitigates differences in chromaticity and minimizes variations in LED lifetime, thereby suppressing the decrease in long-term reliability of the display device by ensuring consistent luminance and optimal operation of micro-LEDs across different areas.
Implementation Method 1
a first LED chip (651) included in one of the plurality of sub-pixels and emitting light at a first luminosity L1, a second LED chip (652) included in the one of sub-pixel and emitting light at a second luminosity L2
Implementation Method 2
The luminance EQEL1 is the luminance of the first LED chip when the first LED chip emits light at a current density maximizing an external quantum efficiency, the luminance EQEL2 is the luminance of the second LED chip when the second LED chip emits light at a current density maximizing an external quantum efficiency
Data Source
AI summary
A display device comprises a plurality of pixels arranged in a first direction and a second direction intersecting the first direction, a plurality of sub-pixels included in each of the plurality of pixels, a first LED chip included in one of the plurality of sub-pixels and emitting light at a first luminosity L1, a second LED chip included in the one of sub-pixel and emitting light at a second luminosity L2, a first wiring supplying a first voltage corresponding to the first luminosity L1 to the first LED chip, a second wiring supplying a second voltage corresponding to the second luminosity L2 to the second LED chip. The first luminous intensity L1 of the first LED chip is calculated based on an equation (1) using a chip area S1 and a luminance EQEL1 of the first LED chip,L1=S1×EQEL1 (1).