Pressure Sensor Bridge Circuit Failure Detection
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Solution Overview
Problem
Pressure sensors with diaphragms in semiconductor substrates face challenges in detecting damage caused by excess pressure, such as freeze damage or surge pressure, which can lead to incorrect pressure readings and potential system failures.
Innovation Solution
A pressure sensor design that includes a bridge circuit with four resistor devices on the diaphragm, a detecting unit to monitor output voltages, and a failure detecting unit that determines circuit failure by checking output terminals against predetermined voltage ranges and varying voltages to confirm damage, along with an AD converter for digital conversion and a voltage control unit to adjust voltages for precise failure detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a bridge circuit is used to detect pressure variations, then measurement precision is improved, but reliability deteriorates when excess pressure damages the diaphragm
Solution Approach 1:
The failure detection unit performs preliminary monitoring of the bridge circuit outputs to detect damage early. By continuously checking whether output voltages remain within expected ranges, the system can identify diaphragm damage before it leads to complete system failure, enabling preventive action.
Solution Approach 2:
The system implements feedback by feeding back the bridge circuit output voltages to the failure detection unit. This closed-loop monitoring allows real-time assessment of bridge circuit health, comparing actual outputs against predetermined ranges to detect anomalies indicating diaphragm damage.
2Reliability
If voltage variation is applied to detect bridge circuit failure, then reliability is improved, but device complexity increases
Solution Approach 1:
The voltage control unit serves multiple functions: it provides excitation voltage to the bridge circuit during normal operation and applies voltage variations for failure detection. This multi-functionality reduces overall system complexity despite adding the capability for active failure detection through voltage variation.
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
Enables early detection of diaphragm damage, preventing system failures by accurately determining bridge circuit failures and allowing for timely intervention or repair, thus ensuring reliable pressure measurements.
Implementation Method 1
The bridge circuit has two output terminals, and the variation in the resistance that forms the bridge circuit is detected based on the voltage difference between these two output terminals
Data Source
AI summary
If the bridge circuit fails due to damage of the diaphragm, the damage is detected at an early stage. A pressure sensor comprises: a substrate provided with a diaphragm; a bridge circuit having four resistor devices provided at the diaphragm, the bridge circuit being applied with high-voltage-side voltage and low-voltage-side voltage, and having two output terminals; a detecting unit for detecting a first output at a first output terminal and a second output at a second output terminal, each output terminal being of the bridge circuit; and a failure detecting unit for detecting failure of the bridge circuit based on a detection result at the detecting unit.