Optoelectronic Assembly Short Circuit Detection via Discharge Current
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Solution Overview
Problem
Conventional methods for identifying short circuits in optoelectronic assemblies, particularly in series connections of light emitting diode (LED) elements, are unreliable and require complex or costly wiring setups, as they struggle to accurately detect short circuits without knowing the number of connected LEDs and are susceptible to interference from aging and temperature variations.
Innovation Solution
A method that interrupts the energy supply to a component string and measures the maximum discharge current between input and output, allowing for reliable identification of short circuits without needing to know the number of LEDs in series, using a driver circuit with only one input and one output, and minimizing the influence of aging and temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods use overvoltage or undervoltage at the corresponding OLED as a criterion for defect identification, then short circuits can be detected, but the methods require complex wiring setups and are unreliable in series connections without knowing the number of connected LEDs
Solution Approach 1:
The patent extracts the diagnostic function from the operational circuit by introducing a separate test mode. During normal operation, the OLEDs are driven in series connection. For defect detection, the circuit is switched to a test configuration where the first and second inputs are electrically connected to each other, creating a standalone measurement path that doesn't depend on knowing the number of OLEDs or requiring complex wiring to individual devices.
Solution Approach 2:
The patent implements periodic switching between operational mode and test mode. The circuit alternates between driving the OLEDs normally and performing short circuit detection by connecting the inputs together. This periodic action allows the system to maintain reliable detection capability without permanently increasing wiring complexity, as the test configuration is activated only when needed.
2Ease of operation
If individual defective light emitting diode elements in a series connection are intended to be identified using simple methods, then detection should be straightforward, but this constitutes a particular challenge due to the series connection topology
Solution Approach 1:
The patent introduces an intermediary measurement approach by connecting the first and second inputs together during test mode. This creates a direct measurement path that bypasses the series connection topology challenges. The intermediary connection allows the system to measure the total current flowing through all OLEDs simultaneously, making defect identification simple without being affected by the series connection difficulty.
Solution Approach 2:
The patent makes the driver circuit universal by enabling it to perform both normal driving function and defect detection function using the same hardware. The circuit can operate in series connection mode for driving and automatically switch to test mode for detection, eliminating the need for separate detection equipment or complex individual measurements, thus achieving ease of operation despite the challenging series topology.
3Adaptability or versatility
If flexible control devices have a variable output range allowing a variable number of light emitting diode elements to be connected, then adaptability is improved, but fixed undervoltage identification thresholds cannot be defined in the driver circuit
Solution Approach 1:
The patent implements a dynamic detection approach where the measurement configuration changes based on the operational mode rather than relying on fixed thresholds. In test mode, the inputs are connected together and the system measures the total current dynamically. This dynamic measurement adapts to any number of connected OLEDs automatically, eliminating the need for fixed thresholds while maintaining measurement precision across variable configurations.
Solution Approach 2:
The patent changes the measurement parameter from voltage-based detection (which requires fixed thresholds) to current-based detection in a closed-loop test configuration. By measuring the total current flowing through the series connection when inputs are connected, the system achieves precision independent of the number of OLEDs. The parameter change from voltage to current measurement allows the system to adapt to variable configurations while maintaining accurate defect identification.
Data Source
AI summary
A method for operating an optoelectronic assembly which includes at least one component string having at least one section, wherein the section includes at least one light emitting diode element, is provided. According to the method, the section is supplied with electrical energy, the supply of the section with electrical energy is interrupted, an input of the section is electrically coupled to an output of the section, wherein the section is short-circuited via the electrical coupling of the input to the output, a maximum value of an electrical discharge current which flows via the section is detected, and the fact of whether the section of the component string has a short circuit is determined depending on the detected maximum value.