Scan Circuit Shift Registers with Voltage Stabilization
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Solution Overview
Problem
The leakage currents of switches in scan circuits within display panels cause voltage shifts, leading to operational instability and incorrect output of scan signals, affecting the display panel's performance.
Innovation Solution
The scan circuit design includes a series connection of shift registers with specific switches and capacitors that maintain a stable voltage level on control nodes by providing a first voltage to the control node in each cycle period, preventing voltage shifts and ensuring accurate scan signal output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switches are used in shift registers to generate scan signals, then the scan circuit can operate and control pixels, but leakage currents cause voltage shifts that lead to operational instability
Solution Approach 1:
The patent extracts and addresses the harmful leakage current effect by introducing a dedicated control mechanism. The control unit monitors the voltage at the control node and activates the operating unit to restore voltage when leakage causes voltage shift, effectively separating the signal generation function from the voltage stabilization function.
Solution Approach 2:
The patent implements a feedback mechanism where the control unit continuously monitors the voltage level at the control node and provides feedback control. When the voltage shifts due to leakage current, the control unit detects this change and triggers the operating unit to restore the voltage, creating a closed-loop control system that maintains stable operation.
2Measurement precision
If switches are used to generate scan signals row-by-row, then pixels can be controlled sequentially, but voltage shifts cause incorrect scan signal output
Solution Approach 1:
The patent introduces an intermediary control mechanism between the driving unit and the output. The control unit acts as an intermediary that monitors the control node voltage and coordinates with the operating unit to correct voltage shifts before they affect the scan signal output, ensuring signal accuracy while maintaining operational stability.
Solution Approach 2:
The feedback mechanism ensures that voltage shifts are detected and corrected in real-time, preventing incorrect scan signal output. The control unit monitors the control node and provides feedback control to the operating unit, maintaining precise voltage levels necessary for accurate scan signal generation.
3Device complexity
If a simple shift register structure is used, then device complexity is low, but leakage currents cause voltage instability
Solution Approach 1:
The patent segments the shift register functionality into distinct units: a driving unit for signal generation, a control unit for monitoring, and an operating unit for voltage restoration. This segmentation allows each unit to perform its specific function efficiently, adding minimal complexity while significantly improving voltage stability through specialized control.
Solution Approach 2:
The control unit serves as an intermediary that bridges the simple shift register structure and the voltage stabilization requirement. It monitors the control node voltage and coordinates voltage restoration operations without requiring a complete redesign of the basic shift register architecture, thus maintaining relative simplicity while enhancing reliability.
Data Source
AI summary
A display panel and a scanning circuit are disclosed herein. The scanning circuit includes a plurality of shift registers. Each of the shift registers includes a driving unit, a control unit, and an operating unit. The driving unit is configured to receive a start signal and a driving clock signal, and provide a scan signal to an output end according to the start signal and the driving clock signal. The control unit is configured to provide a second voltage to the output end according to a first voltage on a control node, and to provide the second voltage to a driving end according to the first voltage on the control node. The operating unit is configured to operatively provide the first voltage to the control node according to an operating clock signal after the scan signal is outputted.