Emission Driver Buffering Circuit for Q-Node Stress Control
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Solution Overview
Problem
Display devices experience abnormal pixel driving and image degradation due to improper emission signal supply, leading to increased stress on transistors with high gate-source voltage.
Innovation Solution
An emission driver with reduced transistor count and a Q node controller to manage voltages at the Q and QB nodes, using buffering transistors to mitigate stress and improve reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional emission drivers are used with direct transistor connection to high-potential driving voltage, then the device complexity is reduced, but the transistor stress increases and reliability deteriorates
Solution Approach 1:
A buffering transistor is introduced as an intermediary component between the high-potential driving voltage input terminal and the Q node controller. This buffering transistor isolates the direct connection, preventing high stress from being applied to the Q node controller transistor while still enabling proper voltage control. The intermediary element resolves the contradiction by protecting the critical transistor without significantly increasing overall device complexity.
2Device complexity
If the number of transistors is reduced in the emission driver, then the device complexity decreases, but the ability to control voltage at Q node and QB node deteriorates
Solution Approach 1:
The buffering transistor serves multiple functions simultaneously: it acts as a voltage buffer, provides isolation, enables proper switching control, and maintains voltage levels without requiring additional dedicated components. This multi-functionality allows the emission driver to maintain full voltage control capability while using fewer total transistors, resolving the contradiction between device complexity and operational ease.
3Ease of operation
If high gate-source voltage is applied to transistors for proper emission signal control, then the emission signal control capability is improved, but the transistor stress increases and lifetime decreases
Solution Approach 1:
The buffering transistor is positioned beforehand in the circuit to cushion and absorb the high voltage stress before it reaches the Q node controller transistor. By providing this protective buffer in advance, the critical transistor is shielded from damaging high gate-source voltage conditions while still allowing proper emission signal control to function, thus extending transistor lifetime without sacrificing control capability.
Data Source
AI summary
An emission driver is disclosed. The emission driver includes a Q node controller configured to control a voltage at a Q node by applying a start signal, a carry signal, or a high-potential driving voltage to the Q node responsive to a first clock signal, a QB node controller configured to control a voltage at a QB node by applying the high-potential driving voltage or a low-potential driving voltage to the QB node responsive to the first clock signal, an output buffer configured to output the high-potential driving voltage or the low-potential driving voltage to the corresponding emission line responsive to the voltages at the Q node and the QB node, and a pump controller configured to change the voltage at the Q node according to a second clock signal while the emission signal is output at a turn-on level responsive to the start signal or the carry signal.