Pixel Duty Control for Micro LED Color-Stable PWM Driving
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Micro LED displays using PWM driving methods face issues with color coordinate shifts due to varying current densities, leading to image quality deterioration, and require additional circuitry that increases costs.
Innovation Solution
A pixel control method that adjusts light emission times and duty ratios based on input grayscale values, incorporates ultra-low grayscale modes with increased frame rates, and includes black data insertion periods to maintain image quality without additional circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PWM driving method is used to maintain constant current density, then color coordinate stability is improved, but circuit cost increases due to additional sweep waveform generation circuits
Solution Approach 1:
The patent extracts the essential function of PWM driving (controlling light emission time) while removing the complex sweep waveform generation circuit. Instead, it uses a simple counter circuit to generate duty data that controls the lighting period of pixels based on maximum grayscale values, achieving color stability without the additional circuit complexity.
Solution Approach 2:
The patent uses a counter circuit to generate duty data that copies the grayscale information, creating a simplified version of the PWM control mechanism. The counter generates duty ratios proportional to grayscale values, replicating the essential control function without requiring complex sweep waveform circuits.
2Illumination intensity
If micro LED current density is increased for high luminance, then brightness is improved, but color coordinates shift causing image quality deterioration
Solution Approach 1:
The patent uses periodic light emission control through duty cycles. By controlling the lighting period of pixels in a periodic manner based on grayscale values, it maintains constant current density while achieving desired luminance levels, preventing color coordinate shifts that occur with continuous high current operation.
Solution Approach 2:
The patent changes the control parameter from current density to lighting period duration. Instead of varying current density to control brightness, it maintains constant current density and varies the duration of light emission (lighting period) based on grayscale values, thereby preventing color coordinate shifts while achieving different luminance levels.
3Manufacturing precision
If additional circuitry is added for PWM driving, then image quality is improved, but manufacturing cost increases
Solution Approach 1:
The patent makes the counter circuit perform multiple functions: it generates duty data for PWM control, determines lighting periods based on maximum grayscale values, and controls pixel output without requiring separate sweep waveform generation circuits. This multi-functionality reduces the overall circuit count and manufacturing cost while maintaining image quality.
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
Improves image quality by preventing color coordinate shifts while avoiding increased circuit costs, enabling efficient and high-luminance LED driving with extended lifespan and reduced power consumption.
Implementation Method 1
An electroluminescence display can display an input image by emitting light by itself using light-emitting elements respectively provided in pixels without a backlight
Implementation Method 2
the micro LED has a high turn-on speed, is excellent in light emission efficiency
Data Source
AI summary
A pixel control method may set a maximum grayscale value of one-frame data of an input image as a maximum input grayscale, and match the maximum input grayscale with a maximum output grayscale and match input grayscales equal to or smaller than the maximum input grayscale with grayscales equal to or smaller than the maximum output grayscale. Duty data controlling a lighting period of pixels is selected according to the maximum input grayscale. The maximum input grayscale varies depending on a maximum grayscale value of the input image. The maximum output grayscale is a fixed grayscale value determined according to the number of bits of pixel data. The lighting period of the pixels indicated by the duty data vary depending on the maximum input grayscale. A display device using the pixel control method is also disclosed.