Dual TFT Pixel Cells for Fault-Tolerant LCD Driver Redundancy
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Solution Overview
Problem
Existing fault-tolerant Active Matrix Liquid Crystal Displays (AMLCDs) often result in information loss when a fault occurs, as they typically require shutting down part of the display to maintain functionality, which is inadequate for critical applications like aircraft cockpits where full information display is essential.
Innovation Solution
The implementation of dual TFT switching transistors within each pixel cell, with separate and redundant driver pairs for each transistor, allowing both driver pairs to operate independently and continue displaying information without loss if one pair fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If simple redundancy with two identical displays is used, then fault tolerance is improved, but information loss occurs when one display fails
Solution Approach 1:
The invention segments the display system into two independent drive paths (first and second TFT transistors per pixel) that can operate separately. Each pixel is divided into two sub-pixels, each controlled by its own transistor and driver couplet, allowing one path to fail without affecting the other's ability to display information.
Solution Approach 2:
The invention applies different drive configurations to different parts of the pixel structure. Each pixel contains two distinct TFT transistors with separate gate and source drivers, creating local redundancy where each half of the pixel can be driven independently through its own transistor and associated drivers.
2Reliability
If display sections are partitioned with independent sources, then fault tolerance is improved, but information loss still occurs
Solution Approach 1:
The display is segmented at the pixel level rather than at the section level. Each pixel is divided into two independently controllable sub-pixels with separate TFT transistors and driver couplets, enabling finer-grained fault isolation that prevents information loss while maintaining overall display functionality.
3Speed
If dual gate drive is implemented, then propagation delay is reduced, but fault tolerance is not fully achieved
Solution Approach 1:
The invention segments each pixel into two independently driven sub-pixels with separate TFT transistors and complete driver couplets (gate and source drivers). This segmentation provides both the speed benefits of parallel driving and the fault tolerance of independent failure paths, as each sub-pixel can operate autonomously.
Solution Approach 2:
The display system is pre-configured with redundant driver couplets and dual TFT transistors before any fault occurs. This preliminary redundancy ensures that when a fault happens, the system can immediately switch to the backup path without loss of information or noticeable delay.
4Reliability
If redundant driver pairs are added, then fault tolerance is improved, but device complexity increases
Solution Approach 1:
The invention merges the redundancy function into the existing pixel structure by adding a second TFT transistor and its associated driver couplet to each pixel. This integration approach achieves fault tolerance without requiring separate redundant display sections or complex external redundancy management systems.
Data Source
AI summary
A fault-tolerant display system includes a dual thin film transistor (TFT) panel with pixel cells having two independently-controlled switching transistors; as such, primary source and gate drivers are operative to drive the display with first TFT transistors, while secondary source and gate drivers are operative to drive the display with second TFT transistors. As the display incorporates an additional TFT within the pixel cell which is driven independently, reliability is increased even at the pixel level. In this way, individual pixels of the LCD panel are driven simultaneously and independently by two pairs of source drivers and gate drivers, such that if one of the driver pairs fails due to some fault, the other driver pair can continue to drive the LCD panel without loss of information despite the failure of the first driver pair.