Scan Driver Circuit Reducing Transistor Count
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Solution Overview
Problem
Existing scan driver circuits are complex due to the number of transistors and require a separate reset line, which complicates the scan stage design.
Innovation Solution
A simplified scan stage circuit is achieved by reducing the number of transistors and eliminating the need for a reset line, using a configuration with multiple clock signals and transistors that control voltage nodes based on input signals and clock signals, allowing for efficient scan signal generation without a separate reset transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional scan driver circuits are used, then reliable scan signal generation is achieved, but device complexity increases due to more transistors and separate reset lines
Solution Approach 1:
The patent combines the reset function with the clock signal function by using the same clock signal lines to perform both clocking and reset operations. The clock signal's natural transition edges are utilized to automatically reset the circuit nodes, eliminating the need for separate reset lines and transistors while maintaining reliable scan signal generation.
Solution Approach 2:
The clock signal is designed to serve multiple functions simultaneously: it provides the timing clock signal for scan operation and also acts as a reset signal for the circuit nodes. This multi-functionality reduces the number of dedicated reset components needed in the circuit.
2Manufacturing precision
If more transistors are used in scan stages, then better voltage control is achieved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The circuit nodes automatically reset themselves using the clock signal transitions. When the clock signal transitions, it naturally discharges or resets the voltage at the nodes without requiring additional control transistors, achieving voltage control with fewer active components.
Solution Approach 2:
The reset function is performed periodically along with the clock signal cycles. Instead of continuous reset control requiring additional transistors, the circuit leverages the periodic nature of the clock signal to automatically reset nodes at appropriate intervals, reducing transistor requirements while maintaining voltage control precision.
Data Source
AI summary
A scan driver includes scan stages, an n-th scan stage of the scan stages includes a first driving circuit, a second driving circuit, and an output circuit. The first driving circuit controls a voltage of a first driving node, based on an input signal and a voltage of a second driving node. The second driving circuit controls the voltage of the second driving node, based on a second clock signal and a first voltage. The output circuit outputs a first clock signal as a scan signal and a carry signal, and outputs a second voltage as the scan signal and the carry signal. The first driving circuit includes a first transistor including a gate electrode electrically connected to the second driving node, one electrode electrically connected to an input line that provides the input signal, and another electrode electrically connected to the first driving node.