Sensor Malfunction Detection via Periodic Current Measurement
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Solution Overview
Problem
Conventional malfunction detection systems are not applicable to sensors outputting pulse signals due to large low-frequency components, making it difficult to eliminate noise and are costly, especially when dealing with variations in manufacturing and temperature, and are not suitable for intermittent or alternating current signals.
Innovation Solution
A malfunction detection system that includes a sensor with a first terminal outputting current to vary voltage levels, a current output unit providing a constant current for judging, and a judging unit that determines sensor malfunction based on voltage thresholds during specific periods, allowing for reduced power consumption and improved accuracy across various sensor outputs, including pulse and alternating current signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a filtering circuit is used to eliminate noise from sensor output, then alternating current signals can be processed, but pulse signals with large low-frequency components cannot be effectively filtered
Solution Approach 1:
The patent changes the detection parameter from voltage-based filtering to current-based measurement. By measuring the current flowing through the sensor during specific time periods when no sensor output is expected, the system can detect malfunctions without being affected by the low-frequency components of pulse signals that plague traditional voltage-based filtering circuits.
Solution Approach 2:
The system performs preliminary detection by measuring current during predetermined time periods before the sensor output occurs. This allows the malfunction detection circuit to capture baseline current values that can be compared against expected ranges, enabling detection of sensor malfunctions before they affect the actual sensor measurement period.
2Measurement precision
If an RC filtering circuit is used to eliminate sensor output components, then the circuit dimension increases and manufacturing variation and temperature variation affect performance
Solution Approach 1:
The patent extracts the malfunction detection function from the signal processing path by using a separate current measurement circuit. Instead of trying to filter the sensor output signal, the system separately measures the current through the sensor during non-output periods, eliminating the need for complex RC filtering circuits and their associated manufacturing and temperature sensitivity issues.
Solution Approach 2:
The patent introduces a current measurement circuit as an intermediary between the sensor and the malfunction detection logic. This intermediary circuit measures current during specific time periods and provides cleaned malfunction indication signals to the detection circuit, avoiding the need for direct voltage filtering of the sensor output.
3Reliability
If bias current is continuously outputted to maintain sensor operation, then sensor functionality is ensured, but power consumption increases
Solution Approach 1:
The patent implements periodic action by outputting the current for judging only during specific time periods when malfunction detection is required, rather than continuously. The current output unit supplies current during predetermined intervals to measure sensor characteristics, then stops outputting when not needed, significantly reducing power consumption while maintaining detection capability.
Solution Approach 2:
The sensor serves dual purposes: it operates as the measurement device during its active periods and as the load for malfunction detection during idle periods. By measuring current through the sensor during non-output periods, the system uses the sensor itself as part of the detection mechanism, eliminating the need for separate continuous bias current sources.
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
The system effectively detects sensor malfunctions in pulse and alternating current signals, reduces costs, and enhances accuracy by controlling output periods and using internal power sources, ensuring reliable malfunction judgment without interrupting sensor functions.
Implementation Method 1
a sensor (10) having a first terminal (INA1), and which outputs a sensor output current (Is) that varies a voltage level of the first terminal (INA1)
Implementation Method 2
a current output unit (31) which varies the voltage level of the first terminal (INA1) by outputting a constant current (Ij) for judging to the sensor (10) via the first terminal (INA1)
Data Source
AI summary
The present invention is applicable to various sensor outputs including pulse signals and reduces cost for detecting malfunction. The malfunction detection system detects a malfunction in a sensor, and the malfunction detection system includes a sensor including a first terminal, and which outputs a sensor output current that varies a voltage level of the first terminal, a current output unit which varies the voltage level of the first terminal by outputting a constant current for judging to the sensor via the first terminal, and a judging unit which judges that the sensor is malfunctioning when the current for judging causes the voltage level of the first terminal to be equal to or higher than a threshold in a period different from a first period where the sensor output current causes the voltage level of the first terminal to be equal to or higher than the threshold.