Gate Driving Circuit Node Setup for Voltage Drop Control
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Solution Overview
Problem
The gate driving circuit in light emitting display apparatuses experiences deteriorated charging characteristics and voltage drops due to threshold voltage changes and leakage currents in thin film transistors, leading to defects in picture quality and reliability.
Innovation Solution
A gate driving circuit with multiple stage circuits, each including control nodes, a node control circuit for managing voltage, and an output buffer circuit to handle scan, sense, and carry signals, which minimizes voltage drops by effectively managing the leakage current through a node setup circuit and optimized TFT configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional gate driving circuit is used with thin film transistors, then the circuit can be manufactured with standard processes, but the charging characteristic of the control node deteriorates due to threshold voltage change and leakage current
Solution Approach 1:
The gate driving circuit is divided into multiple stage circuits (first stage, second stage, etc.), where each stage independently controls a control node. This segmentation allows each stage to be optimized for its specific function, improving charging characteristics while maintaining manageable complexity through modular design.
Solution Approach 2:
A node setup circuit is introduced to preliminarily charge the control node before the main switching operation. This preliminary action ensures that the control node reaches the required voltage level quickly and accurately, preventing charging characteristic deterioration without requiring complex circuit modifications.
2Productivity
If the gate driving circuit operates for extended periods, then more pixels can be driven, but voltage drop due to leakage current increases causing operation errors
Solution Approach 1:
The gate driving circuit employs periodic refreshing of control nodes through the node setup circuit. This periodic action compensates for voltage drops accumulated during extended operation, maintaining voltage stability and preventing operation errors while enabling continuous driving of multiple pixel lines.
Solution Approach 2:
The circuit includes feedback mechanisms where the state of control nodes is monitored and used to trigger refreshing operations. This feedback ensures that voltage levels are maintained within acceptable ranges, preventing cumulative effects of leakage current from causing operational failures.
3Speed
If black image insertion is implemented to shorten response time, then motion picture response improves, but picture quality defects occur due to insufficient charging time of control nodes
Solution Approach 1:
The node setup circuit performs preliminary charging of control nodes before the black image insertion period. This ensures that control nodes are fully charged and ready for immediate operation when the black image period ends, maintaining picture quality while enabling fast response times through the black image technique.
Data Source
AI summary
A gate driving circuit and a light emitting display apparatus comprising the same are discussed, in which a charging characteristic of a control node is improved. The gate driving circuit comprises first to mth stage circuits, wherein each of the first to mth stage circuits includes first to third control nodes, a node control circuit controlling a voltage of each of the first to third control nodes, and an output buffer circuit outputting each of a scan signal, a sense signal and a carry signal in accordance with each of the first to third control nodes, the node control circuit including a node setup circuit charging a first gate high potential voltage in the first control node in response to a first carry signal supplied from a front stage circuit.