Shift Register Unit Bootstrapping for Threshold Voltage Loss
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Solution Overview
Problem
The driving capability of shift registers in display devices is reduced due to the loss of threshold voltage during signal transmission, leading to a narrowing of pulse width in scanning signals, which affects the performance of gate lines in higher definition displays with increasing pixel numbers.
Innovation Solution
A shift register unit comprising a first transistor, an input module, a first control module, a second control module, and an output module, where the input module transmits signals without loss of threshold voltage through a bootstrap function of parasitic capacity, and the control modules manage voltage levels to maintain signal integrity and prevent incorrect output at non-output stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of cascade shift registers is increased to support higher definition displays with more pixels, then the pixel number and display resolution are improved, but the threshold voltage loss increases causing pulse width narrowing and reduced driving capacity
Solution Approach 1:
The patent applies preliminary action by pre-charging the gate electrode of the first transistor to a high potential level before signal transmission. This is achieved through a bootstrapping circuit that charges the gate to a voltage higher than the source voltage, ensuring that the transistor remains fully conductive throughout the signal transmission process and preventing threshold voltage loss from narrowing the pulse width
Solution Approach 2:
The patent changes the voltage parameter of the transistor gate by using a bootstrapping mechanism that dynamically adjusts the gate-source voltage. The gate voltage is elevated above the source voltage level, transforming the transistor's operating point to maintain optimal conductivity conditions throughout the signal transmission, thereby preventing threshold voltage degradation
2Length of stationary object
If the number of TFTs in the shift register is increased to handle more gate lines, then the scanning coverage is improved, but the threshold voltage loss increases causing pulse width narrowing
Solution Approach 1:
The patent applies preliminary action by pre-charging the gate electrode of the first transistor to a high potential level before signal transmission. This is achieved through a bootstrapping circuit that charges the gate to a voltage higher than the source voltage, ensuring that the transistor remains fully conductive throughout the signal transmission process and preventing threshold voltage loss from narrowing the pulse width
Solution Approach 2:
The patent changes the voltage parameter of the transistor gate by using a bootstrapping mechanism that dynamically adjusts the gate-source voltage. The gate voltage is elevated above the source voltage level, transforming the transistor's operating point to maintain optimal conductivity conditions throughout the signal transmission, thereby preventing threshold voltage degradation
3Ease of manufacture
If conventional shift register design is used to reduce cost through GOA technique, then the gate drive IC is eliminated, but the driving capacity is reduced due to threshold voltage loss in signal transmission
Solution Approach 1:
The patent applies preliminary action by pre-charging the gate electrode of the first transistor to a high potential level before signal transmission. This is achieved through a bootstrapping circuit that charges the gate to a voltage higher than the source voltage, ensuring that the transistor remains fully conductive throughout the signal transmission process and preventing threshold voltage loss from narrowing the pulse width
Solution Approach 2:
The patent changes the voltage parameter of the transistor gate by using a bootstrapping mechanism that dynamically adjusts the gate-source voltage. The gate voltage is elevated above the source voltage level, transforming the transistor's operating point to maintain optimal conductivity conditions throughout the signal transmission, thereby preventing threshold voltage degradation
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 solution prevents the loss of threshold voltage, maintaining pulse width and enhancing the drive capability of shift registers, ensuring stable scanning signals for higher definition displays without mistakenly activating gate lines.
Implementation Method 1
when the input module is turned off, a bootstrap function of parasitic capacity between a gate and a drain of the first transistor transmits the signal inputted by a third clock signal end to a second node without loss of threshold voltage of the first transistor
Data Source
AI summary
A shift register unit and a driving method, a gate drive circuit and a display device, the shift register unit comprises a first transistor (T1), an input module (10), a first control module (20), a second control module (30) and an output module (40). The shift register unit and driving method, gate drive circuit and display device are capable of solving the problem that the decrease of drive capacity of the shift register unit is caused by loss of the threshold voltage.