Sensor Diagnostic Circuit Offset Compensation
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Solution Overview
Problem
Existing sensor systems, particularly magnetic sensors, face challenges in providing reliable diagnostics under critical conditions, often resulting in false positive results due to operational limitations near switching points or thresholds.
Innovation Solution
A sensor device with a diagnostic test circuit that generates and compares multiple diagnostic test signals to a calibrated reference signal, using a control circuit to produce a diagnostic signal, thereby enhancing diagnostic capabilities and reliability by defining upper and lower specification limits to manage sensor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing sensor systems operate near switching points or thresholds for diagnostic testing, then diagnostic coverage is improved, but false positive results increase due to operational limitations
Solution Approach 1:
The patent applies preliminary action by introducing offset voltages before the actual sensing operation to shift the sensor output away from critical switching points. The offset compensation circuit pre-adjusts the signal level, allowing diagnostic testing to be performed without operating the sensor in problematic threshold regions, thereby eliminating false positives while maintaining diagnostic coverage.
Solution Approach 2:
The patent changes the electrical parameters of the sensor system by dynamically adjusting offset voltages and signal levels. By modifying the DC offset component of the sensor output, the system can perform diagnostics at safe operating points away from switching thresholds, then restore normal operating parameters when diagnostics are complete, thus resolving the contradiction between diagnostic needs and measurement accuracy.
2Reliability
If separate circuits are used for sensing and diagnostic functions, then diagnostic capability is improved, but device complexity increases
Solution Approach 1:
The patent implements multi-functionality by designing the offset compensation circuit to serve dual purposes: it compensates for offset errors during normal sensing operation and simultaneously provides diagnostic testing capability. The same circuit components and signal paths are used for both measurement and diagnosis, eliminating the need for separate dedicated diagnostic circuits and reducing overall device complexity.
Solution Approach 2:
The patent merges the diagnostic function with the existing offset compensation circuitry. By combining what would traditionally be separate functions into a single integrated circuit, the system achieves full diagnostic capability without adding separate diagnostic hardware, thus reducing complexity while improving reliability.
Data Source
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AI summary
A sensor device (99) includes a sensor (10) for sensing amounts of a physical quantity, such as an environmental attribute, and providing sensor signals formed in response to the sensed physical quantity. A diagnostic test circuit (20) provides multiple diagnostic test signals (22) each representing a desired response to a particular amount of the physical quantity. A signal circuit (30) selects the sensor signal (12) or the diagnostic test signal (22) and forms a signal circuit output (32). A reference circuit (40) provides a calibrated reference signal (42) corresponding to a threshold amount of the physical quantity. A comparator (50) receives and compares the calibrated reference signal (42) and the signal circuit output (32) to form a comparison signal (52). A control circuit (60) controls the signal circuit (30), reference circuit (40), and diagnostic test circuit (20) and receives the comparison signal (52) to output a sensor device sensor signal (64) or sensor device diagnostic signal (62).