Micro LED Display Pixel Gradation Control Across Area, Time, and Current
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Solution Overview
Problem
Existing display technologies face challenges in controlling pixel gradation effectively, particularly in micro LED display devices, due to issues with emission wavelength shifts and brightness adjustments based on external illuminance, which affect image quality.
Innovation Solution
A display device with a gradation control circuit that controls pixel gradation using a combination of first and second LED chips, employing a multi-subframe period approach to adjust light emitting area, emission time, and current value based on illuminance detection, allowing for adaptive gradation control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If OLEDs are used for display, then high contrast and no backlight requirement are achieved, but reliability deteriorates due to organic compound deterioration
Solution Approach 1:
The patent uses multiple short-lived LED chips (first LED chip and second LED chip) that can be individually replaced. Each LED chip has a relatively short lifespan, but by having multiple chips per pixel, the system maintains reliability through redundancy - when one chip deteriorates, the other can compensate or be replaced without replacing the entire display device.
2Reliability
If micro LED chips are used, then reliability and brightness are improved, but emission wavelength shifts and gradation control difficulty worsen
Solution Approach 1:
The patent divides each pixel into multiple independent LED chips (first LED chip and second LED chip), each capable of independent control. This segmentation allows the gradation control circuit to manage wavelength shifts and brightness variations by independently adjusting individual chips, simplifying the overall control complexity while maintaining high reliability.
Solution Approach 2:
The patent employs a gradation control circuit that dynamically adjusts multiple parameters (light emission time, current value, light emitting area) of individual LED chips based on detected external illuminance. This parameter adjustment strategy compensates for emission wavelength shifts and maintains accurate gradation control despite the inherent variability of multiple LED chips.
3Device complexity
If single LED chip is used per pixel, then device complexity is reduced, but gradation control precision and adaptability to external light deteriorate
Solution Approach 1:
The patent segments each pixel into multiple independently controllable LED chips, enabling finer gradation control. The gradation control circuit can precisely adjust the brightness and emission characteristics of each chip individually, achieving higher gradation precision and better adaptability to external light conditions without significantly increasing overall device complexity.
Solution Approach 2:
The patent incorporates an illuminance detection portion that provides feedback about external light conditions to the gradation control circuit. This feedback mechanism enables the system to dynamically adjust the multiple LED chips' emission characteristics, maintaining precise gradation control and image quality across varying external illuminance levels.
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
The solution enables precise gradation control that adapts to external light conditions, maintaining image quality and brightness, thereby enhancing the performance of micro LED display devices.
Implementation Method 1
The pixel includes a first LED chip and a second LED chip... the gradation of the pixel is controlled by a light emitting area of each of the first LED chip and the second LED chip
Data Source
AI summary
A display device includes a display area including a plurality of pixels, and a gradation control circuit configured to control a gradation of the pixel based on a gradation control mode. Each of the plurality of pixels includes first and second LED chips. One frame period of the gradation control mode includes a first to third subframe periods. In the first subframe period, the gradation of the pixel is controlled by a light emitting area of each of the first and second LED chips. In the second subframe period, the gradation of the pixel is controlled by a light emission time of each of the first and second LED chips. In the third subframe period, the gradation of the pixel is controlled by a current value supplied to each of the first and second LED chips.