Bi-directional Shift Registers for LCD Color Washout
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Solution Overview
Problem
Large-size LCD devices with bi-directional shift registers face challenges in maintaining display quality due to color washout issues and inefficiencies in charge sharing processes, particularly when using the GOA technique, which requires multiple scan circuits for precharge and bi-directional scanning, leading to incorrect functioning.
Innovation Solution
The implementation of a display device with a bi-directional shift register set coupled between dummy shift register sets, utilizing a directional start pulse signal generator to enable main and sub gate lines, allowing for correct operation in both forward and reverse scan modes by delaying gate driving signals relative to charge-sharing signals, ensuring proper charge sharing and reducing color washout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If bi-directional shift registers are used with GOA technique for precharge and bi-directional scanning, then device integration and area utilization are improved, but the shift registers cannot function correctly due to timing conflicts between forward and reverse scan modes
Solution Approach 1:
The patent introduces dummy shift registers that perform precharge operations in advance before the actual scanning process. By separating the precharge function into dedicated dummy registers, the timing conflicts between forward and reverse scan modes are eliminated, allowing the bi-directional shift registers to function correctly in both scanning directions.
2Ease of operation
If multiple scan circuits are implemented for precharge and bi-directional scanning, then charging functionality is improved, but device complexity and circuit quantity increase
Solution Approach 1:
The patent merges the precharge function with the dummy shift registers that are already part of the bi-directional scanning structure. Instead of adding separate precharge circuits, the dummy registers are configured to perform both precharge and scanning functions, thereby improving charging functionality without significantly increasing device complexity.
3Ease of manufacture
If charge sharing is implemented to improve color washout, then display quality is improved, but timing synchronization between gate lines becomes difficult with bi-directional scanning
Solution Approach 1:
The patent segments the gate line control into main gate lines and dummy gate lines, with dedicated bi-directional shift registers for each. This segmentation allows independent timing control of charge sharing operations on main gate lines while dummy gate lines handle precharge timing, thereby maintaining display quality without timing synchronization conflicts in bi-directional scanning modes.
Data Source
AI summary
A display device having bi-directional shift registers is disclosed. The display device includes a display panel, a first dummy shift register set, a second dummy shift register set, a third dummy shift register sets, a fourth dummy shift register sets, a first valid shift register set coupled between the first dummy shift register set and the second dummy shift register set, a second valid shift register set coupled between the third dummy shift register set and the fourth dummy shift register set, and a first directional circuit coupled to a first valid register in the first valid register set and the third dummy shift register set.