Gate Shift Register Bidirectional Control Floating Prevention
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Solution Overview
Problem
Existing gate shift registers are unable to perform bidirectional operations, leading to floating and degradation of discharge thin film transistors due to leakage charges, which affects the stability and lifespan of the register.
Innovation Solution
A gate shift register design that includes a scan direction controller, node controller, floating prevention unit, and degradation prevention strengthening unit, utilizing multiple thin film transistors to manage voltage levels and prevent floating, with a 6-phase cycle clock system to ensure stable operation in both forward and reverse shift modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a bidirectional control circuit is added to enable bidirectional shift operation, then the adaptability of the gate shift register is improved, but the discharge TFT becomes floated and degraded due to leakage charges
Solution Approach 1:
The patent applies preliminary anti-action by introducing a floating prevention unit that proactively applies a low potential voltage to the gate electrode of the discharge TFT before leakage charges can accumulate and cause abnormal turn-on. This preventive measure counteracts the harmful floating effect before it can degrade the discharge TFT, thus maintaining reliability while preserving bidirectional operation capability
Solution Approach 2:
The floating prevention unit acts as an intermediary between the bidirectional control circuit and the discharge TFT. It mediates the conflict by applying a low potential voltage to the gate electrode of the discharge TFT, preventing direct harmful interaction between the control circuit and the transistor, thus protecting the discharge TFT from degradation while allowing bidirectional operation
2Device complexity
If the gate electrode of the discharge TFT is floated during shift direction conversion, then the bidirectional control is simplified, but leakage charges accumulate causing the voltage to exceed threshold voltage
Solution Approach 1:
The patent converts the harmful floating state into a beneficial controlled state by using the floating prevention unit to deliberately apply a low potential voltage to the gate electrode. This transforms the uncontrolled floating condition (which causes harm) into a controlled low potential state (which prevents harm), thus eliminating leakage charge accumulation while maintaining bidirectional control functionality
3Stability of the object's composition
If the discharge TFT is held in turn-off state, then the output signal can be held at low level, but the floated gate electrode causes abnormal turn-on
Solution Approach 1:
The floating prevention unit applies preliminary anti-action by proactively maintaining the gate electrode at a low potential voltage level, preventing the discharge TFT from abnormally turning on due to leakage charges. This ensures the discharge TFT remains reliably in the intended turn-off state, thus maintaining output signal stability at low level
Data Source
AI summary
A gate shift register and a display device using the same are disclosed. The gate shift register includes a plurality of stages that receive a plurality of gate shift clocks and sequentially output a scan pulse. A k-th stage of the plurality of stages includes a scan direction controller for converting a shift direction of the scan pulse in response to carry signals of previous stages input through first and second input terminals and carry signals of next stages input through third and fourth input terminals, a node controller for controlling charging and discharge operations of each of Q1, Q2, QB1, and QB2 nodes, a floating prevention unit for applying a low potential voltage to a gate electrode of a discharge TFT based on a voltage of the QB1 node or the QB2 node, and an output unit for outputting first and second scan pulses.