AMOLED Shift Register Anti-Leakage Circuit Design
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Solution Overview
Problem
Existing shift registers in active matrix organic light-emitting diode (AMOLED) panels face issues with erroneous output of light-emitting cascade signals due to leakage currents, leading to instability in voltage levels and potential errors in light emission control.
Innovation Solution
The proposed shift register incorporates a voltage regulating circuit, a light-emitting cascade output circuit, a light-emitting driving output circuit, and anti-leakage circuits to precisely control voltage levels at various nodes, ensuring stable operation and preventing leakage currents from affecting the light-emitting cascade signal output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional shift register circuits are used in AMOLED panels, then the device complexity is reduced, but leakage currents cause erroneous output of light-emitting cascade signals and voltage level instability
Solution Approach 1:
The shift register circuit is segmented into multiple functional modules: voltage regulating circuit (with first and second voltage regulating units), light-emitting cascade output circuit, light-emitting driving output circuit, and anti-leakage circuits. Each module performs a specific function, allowing precise control of voltage levels at different nodes while managing leakage currents independently, thus improving signal stability without excessive complexity
Solution Approach 2:
The patent introduces intermediate voltage regulating units and anti-leakage circuits as mediator components between the clock signal inputs and the light-emitting cascade signal output. These intermediary components actively manage voltage levels and suppress leakage currents, preventing erroneous outputs while maintaining overall circuit functionality
2Reliability
If voltage regulation circuits are added to control voltage levels, then signal output stability is improved, but the device complexity increases
Solution Approach 1:
The voltage regulating circuit applies local quality control by having different voltage regulating units (first voltage regulating unit with first and second transistors, second voltage regulating unit with third and fourth transistors) that independently control voltage levels at specific nodes (first node and second node). Each unit is optimized for its local function, improving overall voltage stability without requiring a complete circuit redesign
Solution Approach 2:
The patent merges multiple functions into integrated circuit blocks: the voltage regulating circuit combines multiple transistor-based voltage control units, the anti-leakage circuits combine protection transistors (fifth and sixth transistors), and these are integrated with the cascade output circuit. This merging reduces the number of separate components while achieving comprehensive voltage control and leakage protection
Data Source
AI summary
A shift register is provided to include: a voltage regulating circuit to adjust voltages at first and second nodes; a light-emitting cascade output circuit to write a second operating voltage from a second power terminal to a light-emitting cascade signal output terminal in response to control of the voltage at the first node, and write a first operating voltage from a first power terminal to the light-emitting cascade signal output terminal in response to control of the voltage at the second node; a light-emitting driving output circuit to write a third operating voltage from a third power terminal to a light-emitting control driving signal output terminal in response to control of the voltage at the first node, and write a fifth operating voltage from a fifth power terminal to the light-emitting control driving signal output terminal in response to control of the voltage at the second node; and a first anti-leakage circuit to write a fourth operating voltage from a fourth power terminal to a first anti-leakage node in response to control of the voltage at the second node.