Micro LED Pixel Circuit With PWM Driving Without Extra Data Lines
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Solution Overview
Problem
Existing pixel circuits for micro LEDs face challenges in high-speed digital driving for high resolution due to complexity and the need for additional data lines, leading to potential color deviation and reduced efficiency.
Innovation Solution
A pixel circuit design that enables pulse width modulation (PWM) driving without additional data lines, utilizing a simplified configuration with transistors and a PWM driver to adjust lighting time based on data voltage, and includes a sensing circuit for threshold voltage compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PWM driving is implemented using conventional pixel circuits with constant current sources, then color deviation is reduced, but device complexity increases and additional data lines are required
Solution Approach 1:
The patent combines the PWM driving function with the existing transistor structure by utilizing the gate electrode of the first transistor to receive PWM control signals. This merging approach integrates the constant current source functionality and PWM modulation into a unified circuit configuration, eliminating the need for separate constant current source circuits and additional data lines while maintaining color consistency.
Solution Approach 2:
The first transistor serves multiple functions: it acts as the primary switching element for current control, receives PWM control signals through its gate electrode for pulse width modulation, and enables grayscale representation through adjusted lighting time. This multi-functionality eliminates the need for dedicated constant current source circuits and additional data lines, reducing device complexity while maintaining color consistency.
2Reliability
If PWM driving is implemented with additional data lines and constant current sources, then color deviation is corrected, but manufacturing cost and device complexity increase
Solution Approach 1:
The patent merges the PWM control functionality directly into the existing transistor gate structure, combining what would traditionally require separate constant current source circuits and additional data lines into a single integrated configuration. This reduces the number of manufacturing steps and component assembly requirements.
Solution Approach 2:
The patent extracts and eliminates unnecessary components from the conventional PWM circuit design by using the existing transistor gate electrode for PWM control instead of requiring separate constant current source circuits and additional data lines. This extraction simplifies the manufacturing process while maintaining color accuracy.
3Reliability
If conventional pixel circuits are used for micro LED driving, then circuit functionality is achieved, but high-speed driving for high resolution is difficult due to complexity
Solution Approach 1:
The patent merges the PWM control signals directly into the gate electrode of the first transistor, eliminating intermediate circuit stages and reducing signal transmission delays. This integrated configuration enables faster response times and supports high-speed driving requirements for high-resolution displays while maintaining full circuit functionality.
Data Source
AI summary
A pixel circuit may include: a first transistor including a first electrode connected to a first node, a gate electrode connected to a second node, and a second electrode connected to a third node; a light-emitting element connected to the third node; and a pulse width modulation (PWM) driver connected to the first transistor and configured to adjust a lighting time of the light-emitting element according to a data voltage of pixel data. A first power line to which a pixel driving voltage is applied is connected to the first node. An anode electrode of the light-emitting element is connected to the third node, and a cathode electrode of the light-emitting element is connected to a second power line to which a ground voltage lower is applied in a display mode. A display device including the pixel circuit is also disclosed.