Shift Register Driving Node Segmentation for LCD Fault Isolation
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Solution Overview
Problem
Conventional single-stage shift registers in liquid crystal display panels face operational issues due to signal errors and shorts, causing abnormal voltage levels in driving nodes, which affect the normal operation of subsequent stages and complicate testing procedures.
Innovation Solution
A single-stage shift register with an individual driving node, incorporating a driving output unit that outputs a driving pulse signal independent of the self-feedback module's voltage level, ensuring correct operation even with signal errors or shorts, and facilitating fault detection and correction during testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the conventional shift register uses a shared driving node for both outputting node N and driving node N+1 ST, then the circuit complexity is reduced, but the reliability deteriorates because signal errors or shorts in node N cause abnormal voltage levels in node N+1 ST
Solution Approach 1:
The patent divides the shared driving node into separate independent nodes: outputting node N and driving node N+1 ST. This segmentation isolates the nodes so that signal errors or shorts in node N cannot affect node N+1 ST, thereby improving reliability while maintaining acceptable circuit complexity through the use of transistors T102 and T103 for isolation.
2Device complexity
If the shift register uses the conventional configuration where transistors T102 and T103 control both nodes, then the device complexity is minimized, but the difficulty of detecting and measuring faults increases because faults in node N cannot be isolated from node N+1 ST
Solution Approach 1:
By segmenting the driving node into separate outputting node N and driving node N+1 ST with isolation transistors, the patent enables independent testing and fault detection for each node. Test signals can be applied to node N+1 ST without being affected by faults in node N, significantly improving fault detection capability.
3Productivity
If the shift register operates with coupled nodes N and N+1 ST, then the productivity is maintained through continuous operation, but the stability deteriorates because voltage levels in node N+1 ST synchronously change with node N even when node N has errors
Solution Approach 1:
The patent segments the coupled nodes into independent units with isolation transistors T102 and T103. This allows node N+1 ST to maintain stable voltage levels independent of node N's voltage fluctuations, ensuring stable operation even when node N experiences errors or shorts.
Solution Approach 2:
Transistors T102 and T103 act as intermediary elements between node N and node N+1 ST. These intermediary transistors control the coupling between nodes, allowing isolation when needed while permitting normal signal transmission during correct operation, thus maintaining both productivity and stability.
Data Source
AI summary
A shift register having individual driving nodes is disclosed. The shift register includes a first clock pull-down module, a second clock pull-down module, a key pull-down module, a self feedback module, and a driving output unit. The first clock pull-down module is used to pull-down the potential of a gate line to a low voltage when the first clock signal is in a high voltage level. The second clock signal pull-down module pulls down the potential of the gate line to the low voltage when the second clock signal is in a high voltage level. The key pull-down module rapidly pulls down the potential of the gate line to the low voltage level after the gate line outputs an output signal. The self feedback module is used to output a driving signal to the key pull-down module. The driving signal output unit outputs a next stage driving signal which is irrelative to the operation of the previous stage shift register.