Scan Driver Short Circuit Detection for LED Displays
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Solution Overview
Problem
Conventional LED display driving methods alleviate ghosting and cross-channel coupling issues but introduce the short circuit caterpillar phenomenon, degrading display quality.
Innovation Solution
A scan-type display apparatus with a common cathode LED array and a scan driver featuring multiple scan driving circuits, each with a voltage generator and detector, capable of short circuit detection by analyzing voltage levels and detection timing signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional line scan driving method is used for LED display, then ghosting phenomenon and cross-channel coupling problems are alleviated, but short circuit caterpillar phenomenon occurs degrading display quality
Solution Approach 1:
The patent applies preliminary action by detecting short circuit conditions before they propagate through the display. The detection circuit monitors voltage at the output terminal of each scan driving circuit during specific time periods (first time period when clamp voltage is output, second time period when common voltage is output) to identify short circuits early, preventing the caterpillar phenomenon from developing and degrading display quality.
Solution Approach 2:
The patent introduces an intermediary detection mechanism between the scan driving circuits and the LED array. The detection circuit acts as a mediator that monitors voltage conditions and generates detection signals to identify short circuits, serving as an intermediate layer that prevents harmful short circuit effects from propagating through the entire display system.
2Measurement precision
If voltage monitoring is performed continuously to detect short circuits, then detection accuracy is improved, but power consumption and system complexity increase
Solution Approach 1:
The patent implements periodic action by performing voltage monitoring only during specific time periods within each scanning cycle. The detection circuit monitors voltage during the first time period (when clamp voltage is output) and the second time period (when common voltage is output), rather than continuously monitoring. This periodic detection approach maintains detection accuracy while reducing power consumption and system complexity compared to continuous monitoring.
Data Source
AI summary
A scan-type display apparatus includes an LED array and a scan driver. The LED array has a common cathode configuration, and includes multiple scan lines, multiple data lines and multiple LEDs. The scan driver includes multiple scan driving circuits. Each scan driving circuit includes a voltage generator and a detector. The voltage generator has an output terminal that is connected to the scan line corresponding to the scan driving circuit, and is configured to output one of a common voltage and a clamp voltage at the output terminal of the voltage generator. The detector is connected to the output terminal of the voltage generator, and generates a detection signal that indicates whether any one of the LEDs connected to the scan line corresponding to the scan driving circuit is short circuited based on a voltage at the output terminal of the voltage generator and a detection timing signal.