LED Branch Testing via Constant Current Voltage Ratio
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Solution Overview
Problem
Existing methods for testing light-emitting diode (LED) functionality in emergency lighting systems are unreliable due to the risk of damage from short circuits and the complexity of storing standard current values, which can be affected by LED aging and non-linear voltage-current characteristics.
Innovation Solution
The method involves impressing a constant electrical current on an LED branch with at least two parallel LEDs, each with a resistor in series, and measuring voltage across the branch in both operating and test states, allowing for safe and reliable functionality testing without relying on stored standard values, using a variable constant current source and a voltage measuring circuit to assess voltage ratios for error detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant voltage source is connected to the circuit arrangement in the test state to measure current strength, then the functionality of light-emitting diodes can be tested, but significant current may develop in the event of a short circuit leading to damage of other circuit parts
Solution Approach 1:
The patent changes the electrical parameter from constant voltage to constant current during testing. By using a constant current source instead of a constant voltage source, the current is limited to a safe level even if LEDs are short-circuited, preventing damage while still enabling functionality testing through voltage measurements.
Solution Approach 2:
The patent substitutes the measurement approach by measuring voltage across the LED branch instead of measuring current. This substitution allows functionality testing without requiring a constant voltage source that could cause harmful current overload in case of short circuits.
2Reliability
If standard current values are stored for comparison to detect errors, then the functionality can be assessed, but the method becomes complex and unreliable due to current changes from LED aging
Solution Approach 1:
The patent makes the testing method self-adapting by using voltage measurements under constant current conditions. The method automatically compensates for LED aging and individual characteristics because the voltage ratio comparison is independent of absolute current values, eliminating the need for stored standard values and complex calibration systems.
Solution Approach 2:
The patent changes from current measurement to voltage measurement under constant current conditions. This parameter change simplifies the testing method by eliminating the need to store and compare standard current values, as voltage ratios directly indicate functionality without being affected by LED aging or manufacturing variations.
3Ease of operation
If current levels are compared to stored standard values for error detection, then functionality can be assessed, but the method fails to account for LED aging and non-linear voltage-current characteristics
Solution Approach 1:
The patent changes the measurement parameter from current to voltage while maintaining constant current excitation. This approach reliably detects errors by comparing voltage ratios between operating and test states, making the method independent of LED aging effects and non-linear voltage-current characteristics that plague current-based comparison methods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach prevents overloading and damage during testing, provides a robust and versatile method for detecting faults, and is less dependent on structural design or aging effects, enabling reliable detection of short circuits and line breaks with minimal parameter fluctuations.
Implementation Method 1
a constant electrical current is impressed on the light-emitting diode branch
Implementation Method 2
at least one voltage is measured over the light-emitting diode branch as the electrical quantity
Implementation Method 3
a plurality of light-emitting diodes... for the functionality of its light-emitting diodes
Implementation Method 4
light-emitting diode branch having a plurality of light-emitting diodes
Data Source
AI summary
The method involves testing electrical magnitude of a circuit device using direct or indirect measurement, where LED branches (2) comprise LEDs (3) that are connected in series with a resistor (4). Constant electric current (I2) is injected as electrical signals in an operation and test mode, and voltage over the LED branches is measured. The LED branches are tested for efficiency of the LEDs under consideration in the operating and test state of measured voltages (U1, U2), where current intensity of another electric current (I1) is smaller than current level of the former electric current. An independent claim is also included for a circuit device.