Shift Register TFT Segmentation for Display Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional shift registers in display manufacturing suffer from high power consumption, limited bandwidth, and reliability issues due to rapid aging of TFTs, leading to malfunction and increased threshold voltage, which affects the performance and lifespan of gate driving circuits in displays.
Innovation Solution
A shift register design comprising multiple sub-units connected in cascade, where the second and third TFTs are alternately turned on to transmit signals, and a reset control module is reused across stages to control TFTs, reducing the number of control modules needed and minimizing area occupancy while improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional shift register sub-unit uses only one TFT (T2) to transmit the low level signal from VGL to OUT, then the structure is simple, but the TFT undergoes rapid aging and threshold voltage increases gradually, leading to failure
Solution Approach 1:
The patent divides the signal transmission function into two separate TFTs (T2 and T3) instead of using a single TFT. T2 transmits the low level signal from VGL to node QB, while T3 transmits the signal from node QB to OUT. This segmentation distributes the aging stress and prevents any single TFT from undergoing rapid degradation, thereby improving reliability while maintaining structural simplicity.
2Device complexity
If the shift register adopts a dynamic circuit with N-type or P-type TFTs to reduce structure complexity and area, then the structure is compact, but the TFT threshold voltage increases gradually during aging, causing malfunction
Solution Approach 1:
The patent segments the signal transmission path into two TFTs (T2 and T3), which distributes the aging effect and prevents threshold voltage drift from causing malfunction. This segmentation approach maintains the compact dynamic circuit structure while significantly improving operational stability and reliability.
3Ease of operation
If a conventional shift register uses separate control modules for each TFT, then each TFT is independently controlled, but the occupied area increases and cost increases
Solution Approach 1:
The patent implements multi-functionality by using the same reset control module to control both T2 and T3 TFTs. The reset control module receives clock signals and level signals to sequentially activate T2 and T3, eliminating the need for separate control modules for each TFT. This reduces the occupied area and cost while maintaining precise control over the signal transmission process.
4Use of energy by moving object
If the shift register uses a static circuit with many TFTs to achieve low power consumption and large bandwidth, then power consumption is low and bandwidth is large, but the structure becomes complex and area increases
Solution Approach 1:
The patent employs a dynamic circuit approach with carefully designed timing control. The reset control module sequentially activates T2 and T3 based on clock signals, creating a dynamic operation mode that achieves low power consumption and large bandwidth. This dynamic operation reduces the number of simultaneously active TFTs, thereby reducing structural complexity and occupied area while maintaining performance.
Data Source
AI summary
A shift register, comprising a plurality of shift register sub-units connected in cascade, each of the plurality of shift register sub-units comprising first to third TFTs, an eleventh TFT, a first capacitor and a first reset control module for controlling the second TFT to be turned on or off. Besides the shift register sub-unit at a first stage, for each of the shift register sub-units at other stages, the second TFT gate control terminal thereof is connected to the third TFT gate control terminal of the shift register sub-unit at a previous stage. Accordingly, a gate driving circuit comprising the shift register and a display comprising the gate driving circuit are provided. Compared with the prior art, reliability of the shift register is highly improved and area occupied by the shift register is smaller.