Level Shifter With Floated Reverse Pad For EMI Resistant Scan Driver
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Solution Overview
Problem
Display devices such as LCDs and OLEDs face challenges in maintaining a smooth output state and reliability of scan signals due to electromagnetic interference (EMI), which affects the characteristics and level of scan signals.
Innovation Solution
A level shifter with a signal pad for outputting a clock signal and a reverse signal pad with a reverse phase clock signal, where the reverse signal pad is in an electrically floated state, is used in conjunction with a shift register circuit to create a robust scan driver. This configuration includes alternately wired clock and reverse clock signal lines, with differing pulse generation and end times, to mitigate EMI effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional level shifter is used without a floated reverse signal pad, then the circuit structure is simpler, but electromagnetic interference affects the scan signal characteristics and reliability
Solution Approach 1:
The reverse signal pad is extracted from the conventional connected state and placed in a floated (disconnected) state. This extraction eliminates the harmful electromagnetic interference pathway while preserving the necessary signal transmission function through the clock and reverse clock signal lines, thereby improving scan signal reliability without requiring fundamental structural changes.
Solution Approach 2:
The patent converts the potentially harmful electromagnetic interference caused by the reverse signal pad into a beneficial configuration by floating the pad. This transformation uses the presence of the reverse signal pad structure while eliminating its harmful EMI effects, turning what would be a source of interference into a neutral or beneficial element for signal integrity.
2Reliability
If the reverse signal pad is connected to the reverse clock signal line, then the circuit is more complete, but electromagnetic interference degrades scan signal characteristics
Solution Approach 1:
The reverse signal pad is extracted from the connected state and placed in a floated state, removing it from the electromagnetic interference pathway. This extraction eliminates the direct connection that would allow EMI to affect the reverse clock signal line, thereby protecting scan signal characteristics from degradation.
Solution Approach 2:
The floated reverse signal pad acts as an intermediary element that is present in the circuit structure but electrically isolated. This intermediary configuration allows the circuit to maintain its structural completeness while preventing electromagnetic interference from being transmitted through the reverse signal pad to affect scan signal characteristics.
Data Source
AI summary
A display device includes a display panel and a level shifter. The display panel displays images. The level shifter includes a signal pad through which a clock signal to drive the display panel is output and a reverse signal pad through which a reverse clock signal different from the clock signal is output, and the reverse signal pad is in an electrically floated state.