Capacitive Sensor Self-Diagnosis Using Unique Voltage Signatures
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Solution Overview
Problem
Capacitive physical quantity sensors with self-diagnostic functions face challenges in distinguishing between appropriate and abnormal outputs during self-diagnosis, especially when multiple sensors have similar configurations and share the same reference voltage, making it difficult to detect abnormal failures.
Innovation Solution
The capacitive physical quantity detection device employs a differential self-diagnosis voltage for each sensor during simultaneous self-diagnosis operations, allowing for the detection of abnormal failures even when sensors share the same reference voltage, by using a signal processing circuit to differentiate outputs based on unique self-diagnosis voltages applied to the differential amplifier circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple capacitive physical quantity sensors use the same reference voltage for self-diagnosis operation, then the self-diagnosis function can be implemented, but it becomes difficult to distinguish between appropriate and abnormal outputs when sensors have similar configurations
Solution Approach 1:
Each sensor is assigned a unique self-diagnosis voltage value (first self-diagnosis voltage for one sensor, second self-diagnosis voltage for another sensor) that differs from other sensors. This local differentiation in voltage characteristics allows the system to identify which sensor produced which output during self-diagnosis, enabling distinction between appropriate and abnormal outputs even when sensors have similar configurations.
Solution Approach 2:
The patent changes the voltage parameter applied to each sensor during self-diagnosis operation. Instead of using the same reference voltage for all sensors, each sensor receives a different self-diagnosis voltage (different in magnitude or polarity). This parameter variation creates distinct output signatures for each sensor, solving the problem of output indistinguishability while maintaining the self-diagnosis function.
2Productivity
If all sensors perform self-diagnosis operation simultaneously with the same reference voltage, then the self-diagnosis operation can be executed efficiently, but abnormal failures cannot be detected
Solution Approach 1:
The patent applies different self-diagnosis voltage characteristics to each sensor even when they operate simultaneously. One sensor receives a first self-diagnosis voltage while another receives a second self-diagnosis voltage. This local differentiation ensures that each sensor's output can be traced back to its specific input condition, enabling reliable abnormal failure detection during simultaneous self-diagnosis operations.
Solution Approach 2:
The voltage parameter is varied for each sensor during simultaneous self-diagnosis operation. By changing the self-diagnosis voltage value applied to each sensor (different magnitudes or polarities), the system maintains operational efficiency while creating distinguishable output patterns that enable reliable detection of abnormal failures.
3Stability of the object's composition
If the reference voltage is kept almost the same across all sensors for consistency, then system uniformity is maintained, but the ability to detect abnormal failures during self-diagnosis is compromised
Solution Approach 1:
The patent maintains system uniformity by using the same reference voltage during normal operation for all sensors. However, during self-diagnosis operation, it introduces local quality differentiation by applying unique self-diagnosis voltages to each sensor. This approach preserves the stability and uniformity of normal operation while enabling reliable abnormal failure detection during self-diagnosis through localized voltage variations.
Solution Approach 2:
The system dynamically adjusts the voltage applied to each sensor based on the operation mode. During normal operation, all sensors receive the same reference voltage, maintaining uniformity. During self-diagnosis operation, the system dynamically switches to applying different self-diagnosis voltages to each sensor, enabling failure detection. This dynamic adaptation resolves the contradiction between uniformity and detectability.
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 enables the detection of abnormal failures and ensures accurate self-diagnosis even when multiple sensors perform self-diagnosis simultaneously, improving the reliability of capacitive physical quantity detection systems.
Implementation Method 1
a detection unit having a movable electrode movable in accordance with the physical quantity and a fixed electrode facing the movable electrode; a C-V conversion circuit having a differential amplifier circuit... used for detecting a capacitance change between the movable electrode and the fixed electrode
Implementation Method 2
a C-V conversion circuit having a differential amplifier circuit, wherein a first input terminal of the differential amplifier circuit is coupled with the movable electrode, a second input terminal of the differential amplifier circuit inputs a reference voltage therein during a period of a normal operation and inputs a self-diagnosis voltage therein during a period of a self-diagnosis operation
Data Source
AI summary
A capacitive physical quantity detection device comprising a plurality of capacitive physical quantity sensors, wherein each sensor includes: a detection unit having a movable electrode and a fixed electrode; a C-V conversion circuit having a differential amplifier circuit, wherein a first input terminal of the differential amplifier circuit is coupled with the movable electrode, a second input terminal of the differential amplifier circuit inputs a reference voltage and a self-diagnosis voltage therein during a normal operation and a self-diagnosis operation, respectively, and the C-V conversion circuit outputs an output voltage; and a signal processing circuit that performs a signal processing of the output voltage, wherein the reference voltage in each sensor is substantially the same, the plurality of sensors performs the self-diagnosis operation simultaneously, and the self-diagnosis voltage in one of the sensors is a first self-diagnosis voltage that is different in magnitude from the self-diagnosis voltage in another one of the sensors.