Scan Driver Block Segmentation and Bootstrap Stabilization
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Solution Overview
Problem
Display devices are prone to erroneous operations due to static electricity, short-circuit between wires, or coupling, which can cause voltage level changes in scan lines, leading to unstable scan signal output.
Innovation Solution
A scan driver comprising multiple sequentially arranged scan driving blocks, each with specific transistor and capacitor configurations, that output scan signals and input signals with the same waveform, and include bootstrap mechanisms to maintain signal integrity across blocks, minimizing errors from voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional scan driver is used, then the device can operate normally under ideal conditions, but it becomes unstable and prone to erroneous operations when exposed to static electricity, short-circuits, or coupling effects
Solution Approach 1:
The scan driver is divided into multiple independent scan driving blocks (first scan driving block, second scan driving block, etc.), where each block can operate independently. This segmentation ensures that an error in one block does not propagate to other blocks, as each block has its own transistors and capacitors that process signals separately. The scan lines are also segmented into different groups that can be driven independently by different blocks.
Solution Approach 2:
Bootstrap capacitors are pre-charged to specific voltage levels (e.g., ELVDD or ELVSS) before signal transmission. These capacitors store energy in advance to compensate for potential voltage drops or disturbances caused by static electricity, short-circuits, or coupling effects. The pre-charged capacitors provide a buffer that maintains signal integrity even when harmful factors are present.
2Reliability
If voltage level changes occur in scan lines due to external factors, then signal integrity deteriorates, but the invention maintains stable scan signal output through specific transistor configurations
Solution Approach 1:
The invention changes the voltage parameters of the scan signals by using bootstrap capacitors to shift voltage levels. The capacitors store voltage differences and apply them to adjust the scan signal voltage levels, ensuring that even if external factors cause voltage changes, the signals maintain their intended voltage characteristics for proper transistor switching.
Solution Approach 2:
The scan driving blocks are configured with feedback mechanisms where the output of one block can influence the operation of subsequent blocks. The second scan driving block receives signals from the first block and can adjust its operation based on the signal quality received, providing a form of feedback that helps maintain signal integrity despite voltage level changes caused by external factors.
Data Source
AI summary
A scan driver includes scan driving blocks, each including: a first transistor including a gate coupled to a first node and receiving a first clock signal, a first electrode receiving an output control signal, and a second electrode coupled to a scan line at first output; a second transistor including a gate coupled to a second node receiving an input signal according to a second clock signal, and first and second electrodes respectively coupled to a third clock input and the first output; a third transistor including a gate coupled to the first node, a first electrode receiving the output control signal, and a second electrode coupled to an input terminal of a next scan driving block at a second output; and a fourth transistor including a gate coupled to the second node, and first and second electrodes respectively coupled to the third clock input and the second output.