Inverter Circuit Gate Driver Ripple Leakage Reduction
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Solution Overview
Problem
In display devices, particularly organic light emitting display devices, leakage current and malfunction occur due to ripple in the Q node, which affects the performance and reliability of the gate driver circuit.
Innovation Solution
An inverter circuit design is introduced, comprising specific transistors connected between high and low potential voltage lines, which control the charging and discharging of control nodes to prevent ripple and leakage current, utilizing a series connection of transistors in the Qb node discharging unit to manage voltage levels effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional inverter circuit is used to control Q node charging and discharging, then the gate driver can supply scan signals to the display panel, but leakage current and malfunction occur due to ripple in the Q node
Solution Approach 1:
The patent divides the inverter circuit into separate charging and discharging units with independent transistor control. The charging unit uses transistors T1 and T2 while the discharging unit uses transistors T3 and T4, allowing independent optimization of each function to prevent ripple propagation and reduce leakage current.
Solution Approach 2:
The patent implements preliminary discharge control by activating the discharging unit (transistors T3 and T4) before the charging unit (transistors T1 and T2) to ensure complete voltage dissipation. This preliminary action prevents residual charge from causing ripple in subsequent charging cycles.
2Reliability
If multiple transistors are used in series for Qb node discharging to control voltage levels, then ripple and leakage current are reduced, but the device complexity increases
Solution Approach 1:
The patent designs transistors T3 and T4 to serve dual functions: T3 acts as both a discharge switch and a voltage level regulator, while T4 provides both discharge control and ripple suppression. This multi-functionality reduces the need for additional dedicated components, thereby limiting complexity increase.
Solution Approach 2:
The patent applies different transistor configurations to different parts of the circuit based on local requirements. The charging unit (T1, T2) uses a simpler parallel configuration, while the discharging unit (T3, T4) uses a series configuration specifically where precise voltage control is needed to prevent ripple.
3Ease of manufacture
If a single low potential voltage supply is used to power the inverter circuit, then manufacturing costs are reduced, but it becomes difficult to effectively control charging and discharging voltage levels
Solution Approach 1:
The patent changes the operational parameters of the transistors by controlling their gate voltages dynamically. Even with a single low potential voltage supply, the gate voltages of transistors T1-T4 are modulated to effectively create the necessary voltage level differences for charging and discharging operations, maintaining ease of operation without additional voltage supplies.
Data Source
AI summary
An inverter circuit, a gate driver using the same, and a display device according to an embodiment are discussed. The inverter circuit can include a first transistor connected between a high potential voltage line and a first node; a second transistor having a gate connected to the first node and turned on according to a voltage of the first node to charge a second control node to a high potential voltage of the high potential voltage line; a third transistor having a gate connected to a first control node, a first electrode connected to the first node, and a second electrode connected to the second control node; and a fourth transistor having a gate connected to the first control node, a first electrode connected to the second control node, and a second electrode connected to a low potential voltage line.