Pixel Circuit Reducing Transistor Count for Ultra-High-Resolution Displays
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Solution Overview
Problem
Conventional pixel circuits for display devices, which utilize pulse width modulation and internal threshold voltage compensation, require a large number of transistors and capacitors, making them unsuitable for ultra-high-resolution applications.
Innovation Solution
A pixel circuit design incorporating a reduced number of transistors and capacitors, utilizing pulse width modulation and internal threshold voltage compensation, with specific transistor and capacitor configurations to manage power voltages and signals across different periods of a frame, allowing for high integration and efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pixel circuits with 19 or more transistors and 3 or more capacitors are used for PWM driving and internal threshold voltage compensation, then threshold voltage compensation and PWM control are achieved, but device complexity and integration difficulty increase significantly
Solution Approach 1:
The patent merges multiple functions into fewer transistors. Specifically, transistors are designed to perform both switching and compensation functions simultaneously, reducing the total count from 19+ to 11 transistors while maintaining PWM capability and threshold voltage compensation through integrated circuit design
Solution Approach 2:
Transistors in the pixel circuit are designed with multi-functionality, where certain transistors serve multiple purposes such as acting as both switches and compensation elements. This universal design allows the circuit to achieve threshold voltage compensation and PWM control with fewer components, directly addressing the integration challenge
2Device complexity
If the number of transistors and capacitors is reduced for ultra-high-resolution display integration, then device complexity and integration difficulty decrease, but circuit functionality and compensation capability may be compromised
Solution Approach 1:
The patent employs parameter changes in transistor sizing and configuration to maintain compensation effectiveness with fewer devices. By optimizing the electrical parameters such as transistor width-to-length ratios and capacitance values, the circuit achieves proper threshold voltage compensation using only 11 transistors and 2 capacitors, ensuring reliability is not compromised despite reduced component count
3Reliability
If conventional pixel circuits are used, then sufficient compensation capability is achieved, but power consumption and emission stability are insufficient for ultra-high-resolution displays
Solution Approach 1:
The pixel circuit implements periodic action through PWM (pulse width modulation) driving, where the light-emitting element is driven in periodic pulses rather than continuous operation. This periodic driving method, combined with the optimized transistor configuration, reduces average power consumption while maintaining emission stability and brightness control for ultra-high-resolution displays
Data Source
AI summary
A display apparatus includes a gate driver for applying gate signals, a display panel including a pixel circuit including a first transistor for applying a driving current to a second node in response to a voltage of first node, a second transistor configured to connect the first node and the second node, a third transistor for applying a first power voltage, which is changed during a frame period in which the pixel circuit is driven, to the first node, a fourth transistor for applying a data voltage to the third node, a fifth transistor for applying an initialization voltage to the first node, a sweep capacitor for applying a sweep signal to the third node, and a light-emitting element including an anode connected to the second node, and a cathode for receiving a second power voltage, and a data driver for applying a data voltage to the display panel.