Shift Register Discharge Transistor Reliability
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Solution Overview
Problem
Existing shift registers in display apparatuses have insufficient multi-output margin and reliability due to reduced discharge performance and recovery characteristics, especially under high temperature and high humidity conditions, leading to issues with preventing multi-output in one frame of the scan signal.
Innovation Solution
Incorporating a discharge transistor to periodically discharge node voltages and control opposite node voltages based on driving voltages, enhancing the shift register's ability to secure a multi-output margin and improve reliability by adding paths for discharging node voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a related art shift register is configured to output scan signal only at predetermined times in one frame, then the device complexity is reduced, but the reliability and multi-output margin are insufficient
Solution Approach 1:
The shift register is divided into multiple stages (first stage, second stage, third stage, fourth stage) with each stage containing specific transistors for controlled discharge. This segmentation allows different nodes to be discharged at different times, preventing multi-output while maintaining reliability without excessive complexity
Solution Approach 2:
The discharge transistors are configured to discharge node voltages in advance before potential multi-output conditions can occur. By proactively discharging nodes at specific timing (e.g., discharging first node voltage during first clock period, second node voltage during second clock period), the circuit prevents reliability issues before they arise
2Reliability
If discharge performance is reduced under high temperature and high humidity conditions, then the manufacturing precision is maintained, but the multi-output margin becomes insufficient
Solution Approach 1:
The discharge transistors provide preliminary anti-action by actively discharging node voltages before environmental conditions (high temperature and humidity) can cause charge leakage or voltage drift that would lead to multi-output. This preemptive discharge mechanism counteracts the harmful effects of environmental stress
Solution Approach 2:
The shift register implements periodic discharge action through clocked discharge transistors that operate at specific intervals (first clock period, second clock period, etc.). This periodic discharge ensures node voltages are reset before environmental factors can degrade performance, maintaining multi-output margin under varying conditions
3Reliability
If the recovery characteristic from stress is not large, then the device complexity is reduced, but the reliability and multi-output margin are compromised
Solution Approach 1:
The discharge transistor configuration creates a feedback mechanism where the state of nodes (charge levels) automatically triggers discharge actions through the clocked control signals. This feedback ensures that when stress causes voltage drift, the system self-corrects by discharging nodes at appropriate timing, improving recovery characteristic without requiring external control complexity
Data Source
AI summary
Provided are a shift register and display apparatus including the same. A shift register includes a plurality of stages, each of the plurality of stages including: a node controller configured to: periodically discharge a first node voltage generated from a first driving voltage during a first voltage level of a clock signal, and control a second node voltage opposite to the first node voltage based on a second driving voltage, and an output part configured to receive the clock signal to output an output signal based on the first node voltage.