Capacitive Pressure Sensor Resonance Calibration for Sedimentation
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Solution Overview
Problem
Capacitive pressure sensors used in film forming apparatuses face challenges with sedimentation, which affects sensor sensitivity and requires time-consuming calibration, disrupting operations.
Innovation Solution
A pressure sensor system that measures capacitance changes and calculates corrected sensor sensitivity based on resonance point measurements, allowing for automatic calibration and alerting when sedimentation occurs, enabling continuous operation without dismounting the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pressure sensor is used in film forming apparatuses with material gases, then the sensor can measure pressure accurately, but sedimentation occurs on the diaphragm which changes sensor sensitivity
Solution Approach 1:
The patent applies mechanical vibration by measuring the resonance point frequency of the diaphragm. The resonance point measurement unit detects the natural frequency of vibration of the diaphragm, which changes when sedimentation occurs. This vibration-based measurement method enables non-contact detection of diaphragm properties without being affected by the sedimentation that plagues capacitive measurement methods.
Solution Approach 2:
The patent replaces the traditional capacitive measurement system with a resonance frequency measurement system. Instead of measuring capacitance changes that are sensitive to sedimentation, the system measures the mechanical resonance properties of the diaphragm, which remain stable even when sediment accumulates on the surface.
2Measurement precision
If calibration is performed by demounting the pressure sensor, then sensor sensitivity can be corrected, but operation time is lost and calibration becomes time-consuming
Solution Approach 1:
The patent implements self-service calibration by enabling the pressure sensor to perform its own calibration without being removed from the system. The resonance point measurement unit continuously monitors the diaphragm's resonance frequency, and when drift is detected, the system automatically adjusts the sensitivity parameters using the stored relationship between resonance frequency and sensitivity, eliminating the need for manual intervention or system shutdown.
Solution Approach 2:
The patent ensures continuous operation by performing calibration in-situ without requiring the sensor to be demounted. The resonance point measurement and sensitivity correction processes occur while the sensor remains installed and operational, maintaining continuous measurement capability and eliminating downtime associated with traditional calibration methods.
3Reliability
If heating is applied to prevent sedimentation, then sedimentation is reduced, but the sensor still experiences sensitivity changes over time
Solution Approach 1:
The patent implements feedback by continuously monitoring the resonance point frequency of the diaphragm and using this information to detect sensitivity changes. The system establishes a relationship between resonance frequency and sensor sensitivity, and when the resonance frequency shifts indicate sedimentation or sensitivity drift, the system automatically corrects the sensitivity parameters based on the current resonance measurement, providing real-time compensation.
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
Facilitates easy and prompt calibration of pressure sensor outputs due to sedimentation, minimizing downtime and effort, ensuring accurate measurements in film forming processes.
Implementation Method 1
a displacement of the movable region 302a of the diaphragm 302 having received the fluid pressure is converted to a capacitance value between the movable electrode 304 and the fixed electrode 305
Implementation Method 2
a resonance point measurement unit measuring a resonance point of the pressure receiving portion on the basis of the result obtained by performing measurement of a constant pressure using the pressure sensor while a power supply frequency is changed
Data Source
AI summary
Aiming to more easily perform calibration of a sensor output from a pressure sensor, the calibration being necessitated due to the occurrence of sedimentation, a resonance point measurement unit (122) measures a resonance point of a diaphragm (112) on the basis of the result obtained by performing measurement of a constant pressure using the pressure sensor while a power supply frequency is changed, a characteristic calculation unit (123) calculates, on the basis of the measured resonance point, an elastic modulus of the diaphragm (112) at the time of the measurement of the resonance point, and a correction unit (124) calculates a corrected sensor sensitivity resulting from correcting a sensor sensitivity of a sensor chip (101) on the basis of the elastic modulus calculated by the characteristic calculation unit (123).