Micro-LED Pixel PWM Control for Accurate Grayscale
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Solution Overview
Problem
Existing display technologies using pulse amplitude modulation for micro light-emitting diodes suffer from wavelength shifts due to varying driving current amplitudes, leading to inaccurate grayscale representation.
Innovation Solution
A pixel design utilizing pulse width modulation to control the emission time duration of micro light-emitting diodes, employing a light-emitting element driver and a pulse width modulator that generates a pulse width modulation signal based on multiple data bits, ensuring a constant driving current amplitude and precise grayscale representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pulse amplitude modulation method is used to control luminance by varying driving current amplitude, then luminance control is achieved, but wavelength shifts occur leading to inaccurate grayscale representation
Solution Approach 1:
The patent changes the control parameter from current amplitude (PAM) to pulse width/duty cycle (PWM). By maintaining constant current amplitude and varying only the pulse width, the invention eliminates wavelength shifts while achieving luminance control through integrated energy adjustment.
2Measurement precision
If pulse width modulation method is used to control luminance by controlling emission time duration, then grayscale representation accuracy is improved, but device complexity increases due to additional control circuits
Solution Approach 1:
The patent segments the grayscale control into multiple binary data bits (e.g., 8 bits for 256 levels). Each bit controls a specific time slot in the PWM cycle, allowing complex grayscale representation through simple binary combinations and reducing overall control circuit complexity.
Solution Approach 2:
The patent employs periodic PWM cycles where each cycle corresponds to a specific data bit. This periodic structure allows systematic control of emission duration through repeating patterns, simplifying the control logic while maintaining high grayscale precision.
3Measurement precision
If multiple data bits are used to generate pulse width modulation signal, then grayscale precision is enhanced, but signal generation complexity increases
Solution Approach 1:
The patent prepares multiple data bits in advance before the PWM signal generation phase. This preliminary preparation allows the control circuit to simply read and execute pre-processed data during emission control, reducing real-time processing complexity while maintaining high grayscale precision.
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
Accurate grayscale representation is achieved by controlling the pulse width of the driving current, enhancing display quality and consistency in display devices.
Implementation Method 1
a light-emitting element LED through which a driving current ILED flows
Data Source
AI summary
A pixel includes a light-emitting element through which driving current flows, a light-emitting element driver which generates the driving current based on a pulse width modulation signal, and a pulse width modulator which generates the pulse width modulation signal based on first to kth data bits. The pulse width modulator includes a data writer which writes the first to kth data bits in response to a scan signal, a pulse width modulation controller which stores the first to kth data bits and sequentially outputs the first to kth data bits in response to a clock signal, and a pulse width modulation signal generator which generates the pulse width modulation signal in response to the first to kth data bits and an emission signal.