LED Failure Detection via Voltage Difference Comparison
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Solution Overview
Problem
Existing LED failure detection methods are inadequate for timely identification of failures in LED units or strings, particularly in lighting and display applications, where timely replacement is crucial for maintaining performance and preventing damage.
Innovation Solution
A light emitting diode (LED) failure detecting device that includes a driving circuit and a determining circuit, where the determining circuit uses a subtractor and comparing module to generate a determination output indicating whether an LED unit has failed by comparing difference voltages with threshold voltages, allowing for the identification of failed LEDs within an LED array or string.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage comparison method is used to detect LED failures, then detection capability is improved, but device complexity increases due to multiple comparators and logic circuits
Solution Approach 1:
The patent combines multiple voltage comparison operations into a single comparing circuit by using a subtractor to calculate voltage differences and a single comparator to evaluate against threshold values. This merging approach maintains the ability to detect multiple LED failure modes (open circuit, short circuit, abnormal voltage) while reducing the number of discrete components needed.
Solution Approach 2:
The determining circuit is designed to perform multiple detection functions using a unified architecture. The same subtractor and comparator components are used to detect different types of LED failures (open circuit, short circuit, and abnormal voltage conditions) across multiple LED units, making the circuit multi-functional and reducing overall complexity.
2Measurement precision
If multiple voltage comparison operations are performed to detect different LED failure modes, then detection accuracy is improved, but circuit complexity increases
Solution Approach 1:
The patent changes the parameter being compared by using voltage difference (calculated by subtractor) as the input to the comparator, rather than comparing absolute voltages. The comparator evaluates the voltage difference against threshold values that represent different failure conditions. This parameter transformation allows a single comparator to detect multiple failure modes that would otherwise require separate comparison circuits.
3Productivity
If LED units are arranged in matrix with scan lines and data lines, then productivity and coverage are improved, but difficulty of detecting and measuring failures increases
Solution Approach 1:
The patent segments the LED array into multiple LED units that can be independently addressed through scan lines and data lines. Each LED unit can be selectively tested by activating specific row and column selections. The determining circuit processes voltages from selected data lines to evaluate individual LED units, enabling systematic detection across the entire matrix without requiring complex simultaneous monitoring of all LEDs.
Data Source
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AI summary
A light emitting diode (LED) failure detecting device (2) is operatively associated with an LED array (1), and includes a driving circuit (21) and a determining circuit (24). The driving circuit (21) is used to be coupled to scan lines (111-114) and data lines (121-124) of the LED array (1), and drives, based on a first control input corresponding to selection of one of LED units (13) of the LED array (1), the LED units (13) in such a way that a current flows through said one of the LED units (13). The determining circuit (24) generates, based at least on the voltages (Vd1-Vd4) respectively at the data lines (121-124) and on a second control input (S1) corresponding at least to selection of the data line (12n) that is coupled to said one of the LED units (13), a determination output (S2) that indicates whether said one of the LED units (13) is determined to have failed.