Shift Register Circuit With Low Level Maintenance Module
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Solution Overview
Problem
Traditional shift registers in integrated display driver circuits face limitations due to low drift mobility of amorphous silicon TFTs and larger circuit area, which hinder high frame frequency and resolution displays, especially under high temperatures and with smaller threshold voltage TFTs.
Innovation Solution
A shift register design comprising multiple units with a driving module, input module, and low level maintenance mechanism using N-type thin film transistors and capacitances, which charges and discharges signals efficiently, reducing leakage and raising time, and maintaining low level potentials to minimize circuit area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional amorphous silicon TFTs are used in shift register circuits, then manufacturing cost is reduced, but drift mobility is low causing inability to achieve high working frequencies
Solution Approach 1:
The patent changes the material parameter of the TFT from traditional amorphous silicon to oxide semiconductor, which fundamentally alters the drift mobility characteristic. This material parameter change enables high-frequency operation while maintaining compatibility with existing low-cost manufacturing processes for oxide semiconductors.
2Ease of manufacture
If traditional amorphous silicon TFTs are used in shift register circuits, then manufacturing cost is reduced, but circuit area becomes larger
Solution Approach 1:
By changing the TFT material to oxide semiconductor with superior mobility characteristics, the circuit can achieve the same function with smaller transistor dimensions, thereby reducing overall circuit area while maintaining cost-effectiveness through existing manufacturing processes.
3Speed
If capacitance bootstrapping effect is used to enhance driving power, then charging speed of output load is improved, but control electrode boots to high potential causing longer pulse raising time
Solution Approach 1:
The high drift mobility of oxide semiconductor TFTs changes the electrical parameter of the transistor, enabling fast charging of the output load without requiring excessive gate voltage. This parameter change eliminates the need for aggressive capacitance bootstrapping, thus avoiding the high potential bootstrap effect and reducing pulse raising time.
4Power
If large size pull-down tube is used to charge higher output load, then driving capability is improved, but circuit area becomes larger
Solution Approach 1:
The oxide semiconductor TFT's high drift mobility fundamentally changes the current-carrying capability parameter of the transistor. This enables small-sized transistors to deliver the same driving power as large traditional TFTs, thus achieving high driving capability with minimal circuit area.
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
The design enhances the shift register's ability to operate at higher frequencies with reduced leakage and circuit size, making it suitable for high-resolution displays and varying temperature conditions.
Implementation Method 1
the driving module comprises a first thin film transistor and a first capacitance, and a first end of the first thin film transistor connecting to the first clock signal, a second end of the first thin film transistor connecting to the input module, a third end of the first thin film transistor being used for outputting the driving signal, one end of the first capacitance connecting to a second end of the first thin film transistor, another end of the first capacitance connecting to the third end of the first thin film transistor
Implementation Method 2
a first thin film transistor and a first capacitance, and a first end of the first thin film transistor connecting to the first clock signal
Data Source
AI summary
A shift register is disclosed. The shift register comprises a multistage shift register units. Each of the stage shift register unit comprises: a driving module, charging to the driving signal via the first clock signal based on the driving control signal; an input module, outputting the driving control signal based on the second clock signal and the first control signal; a low level maintenance module, keeping the potential of the driving signal at the low level potential of the second reference. The shift register can avoid the leakage from the first output end, decrease the raising time of the driving signal and occupy the small area.