Scan Driver Short Circuit Detection for LED Display
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Solution Overview
Problem
Conventional LED display driving methods alleviate ghosting and cross-channel coupling issues but introduce short circuit caterpillar phenomena, degrading display quality by causing LEDs in the same column to consistently emit light or remain dark due to parasitic capacitance and short circuits.
Innovation Solution
A scan-type display apparatus with a common anode LED array and a scan driver that includes voltage generators and detectors to identify short circuits by outputting input or clamp voltages and detection signals based on timing signals, preventing the short circuit caterpillar phenomenon through appropriate voltage management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LED display driving methods are used to alleviate ghosting and cross-channel coupling, then ghosting and cross-channel coupling problems are reduced, but short circuit caterpillar phenomenon occurs degrading display quality
Solution Approach 1:
The patent applies preliminary action by performing short circuit detection before the short circuit caterpillar phenomenon can degrade display quality. The detection circuit monitors LED status in real-time during the scanning process, enabling early identification of short circuits before they propagate to cause always-bright or always-dark column defects.
Solution Approach 2:
The patent implements feedback through a detection circuit that continuously monitors the state of LEDs and provides real-time information about short circuits. When a short circuit is detected, the system can respond by adjusting scanning patterns or notifying control systems, preventing the propagation of display defects and maintaining overall display quality.
2Reliability
If line scan driving method is used, then ghosting phenomenon is alleviated, but short circuit caterpillar phenomenon is caused
Solution Approach 1:
The patent introduces an intermediary detection circuit between the scan driver and LED array that specifically monitors for short circuit conditions. This intermediary component detects abnormal current or voltage states caused by parasitic capacitance discharge and provides early warning before the short circuit caterpillar phenomenon manifests as visible display defects.
Solution Approach 2:
The patent replaces purely passive line scan driving with an active monitoring system that uses electrical detection circuits to sense short circuit conditions. Instead of relying solely on the mechanical scanning sequence to reveal defects, the system actively detects electrical anomalies that indicate impending short circuit caterpillar phenomena.
3Illumination intensity
If parasitic capacitance discharge is allowed to flow through LED, then LED emits light, but unexpected light emission (ghosting) occurs
Solution Approach 1:
The patent converts the harmful parasitic capacitance discharge that causes ghosting into a detectable signal for short circuit identification. By monitoring the electrical characteristics during the scanning process, the system can distinguish between normal LED operation and abnormal short circuit conditions, transforming a previously harmful effect into a useful detection mechanism.
Data Source
AI summary
A scan-type display apparatus includes an LED array and a scan driver. The LED array has a common anode 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 an input 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.