Shift Register Inverter Unit Bidirectional Scanning
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Solution Overview
Problem
Conventional shift registers in display devices require multiple thin film transistors (TFTs) to adjust scan directions and ensure reliable operation, leading to increased size and complexity, as well as the need for additional components like scan direction adjusters, which complicates the gate driving circuit and enlarges the display device.
Innovation Solution
A shift register and gate driving circuit design that uses a controlled inverter unit coupled with a clock signal, eliminating the need for additional TFTs and simplifying the circuit by using a directional input signal to enable bidirectional scanning and resetting, thereby minimizing TFT deterioration and stabilizing initial driving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional TFTs and scan direction adjusters are added to enable bidirectional scanning and improve reliability, then the reliability and functionality are improved, but the device size and circuit complexity increase
Solution Approach 1:
The inverter unit is designed to perform multiple functions: it inverts the input signal, controls the output signal, and enables bidirectional scanning. By making the inverter unit multi-functional, the patent eliminates the need for separate scan direction adjusters and additional TFTs, thereby reducing circuit complexity while maintaining reliability
Solution Approach 2:
The patent combines the functions of the inverter unit and the scan direction adjuster into a single integrated circuit. The inverter unit now handles both signal inversion and bidirectional scanning control, merging previously separate components to reduce the overall number of TFTs and simplify the circuit structure
2Reliability
If additional TFTs are added to the inverter unit to improve off-characteristics, then the off-characteristics are improved, but the dead space and display device size increase
Solution Approach 1:
The patent changes the operating parameters of the existing TFTs in the inverter unit, specifically using high level voltage Vbias to keep the TFT always turned on. This parameter change improves the off-characteristics without requiring additional TFTs, thereby avoiding an increase in dead space
3Reliability
If the inverter unit is controlled by coupling with a clock signal, then the reliability and bidirectional scanning capability are improved, but the circuit control complexity increases
Solution Approach 1:
The patent uses periodic clock signals (first and second clock signals) to control the inverter unit's operation. The clock signals enable the inverter unit to switch between different operating states reliably, facilitating bidirectional scanning through periodic control actions
Data Source
AI summary
Disclosed are a shift register, and a gate driving circuit including a plurality of shift registers connected in sequence to respectively supply scan signals to a plurality of gate lines of a display device. Each shift register includes: an input unit which outputs a directional input signal having a gate high or low voltage based on an output signal from a previous or subsequent shift register to a first node; an inverter unit which is connected to the first node, generates an inverting signal to a signal at the first node, and outputs the inverting signal to a second node; and an output unit which includes a pull-up unit connected to the first node and activating an output clock signal based on the signal at the first node, and a pull-down unit activating and outputting a pull-down output signal based on a signal at the second node.