Piezoelectric Drive Circuit for In-Operation Deterioration Detection
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Solution Overview
Problem
The existing pressure type flow rate control devices in semiconductor manufacturing facilities and chemical plants face challenges in predicting the deterioration of piezoelectric elements, leading to unpredictable valve failures and unscheduled equipment shutdowns, as the deterioration cannot be accurately detected without stopping normal operations or increasing costs with separate abnormality detection circuits.
Innovation Solution
A driving device with a built-in piezoelectric element deterioration detection circuit that includes a first resistor connected in series with the piezoelectric element, a voltage supply unit, and a measuring unit to calculate the resistance value of the piezoelectric element, allowing for deterioration detection without affecting normal operations, using a control unit to determine if the piezoelectric element has deteriorated by comparing the calculated resistance value with a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate abnormality detection circuit is added to detect piezoelectric element deterioration, then the reliability of detecting deterioration improves, but the device complexity and cost increase
Solution Approach 1:
The patent combines the deterioration detection function with the existing drive circuit by integrating a measurement unit into the same circuit board. The detection circuit shares power supply lines and control resources with the drive circuit, eliminating the need for a completely separate detection system while maintaining detection accuracy through voltage measurement across the piezoelectric element.
Solution Approach 2:
The control circuit board is designed to perform multiple functions: it serves as both the drive circuit for actuating the piezoelectric element and the detection circuit for measuring its electrical characteristics. The measurement unit can switch between drive mode and measurement mode, making the circuit universal and eliminating the need for separate dedicated detection hardware.
2Reliability
If the piezoelectric element is replaced at regular intervals to prevent failure, then the reliability of continuous operation improves, but the productivity decreases due to unnecessary replacements
Solution Approach 1:
The measurement unit continuously or periodically measures the electrical characteristics (voltage, current, impedance) of the piezoelectric element during normal operation to detect early signs of deterioration. By identifying degradation trends before complete failure occurs, the system enables planned maintenance at optimal times rather than forced periodic replacement or unexpected shutdowns.
Solution Approach 2:
The control circuit receives feedback from the measurement unit about the piezoelectric element's electrical characteristics and uses this information to assess its health status. This feedback mechanism allows the system to monitor deterioration in real-time and trigger maintenance alerts only when actual degradation is detected, avoiding unnecessary replacements during the element's useful life.
3Productivity
If the piezoelectric element is measured during normal operation to detect deterioration, then the productivity is maintained, but the measurement precision may be affected by operational conditions
Solution Approach 1:
The control circuit alternates between drive mode and measurement mode in periodic cycles. During measurement mode, the piezoelectric element is not actuated and the measurement unit performs electrical characteristic measurements. This periodic switching allows accurate measurements to be taken during normal operation without continuous interference from drive signals, and the cycle timing is designed to minimize impact on overall system productivity.
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 the detection of piezoelectric element deterioration during normal operation without additional equipment or circuits, allowing for timely replacement and reducing errors by using representative values or slope analysis, thus preventing unscheduled shutdowns and improving maintenance efficiency.
Implementation Method 1
The piezoelectric element 101 is housed in a cylindrical support tube 105 and deformed in the longitudinal direction by on/off controlling of the supply of a predetermined voltage via the connector 102. The deformation of the piezoelectric element 101 causes the deformation of the diaphragm valve element 104
Implementation Method 2
the measuring unit measures a voltage value of the first resistor, in a state where a predetermined voltage is supplied from the voltage supply unit, and the control unit calculates a resistance value of the piezoelectric element from the voltage value obtained by measurement of the measuring unit
Data Source
AI summary
The driving device includes a piezoelectric element, a power supply unit, a first resistor, a second resistor, a measuring unit and a control unit, wherein resistance values of the first resistor and the second resistor are smaller than an insulating resistance value of the piezoelectric element, the measuring unit measures, a voltage across the first resistor (voltage between a first terminal and a second terminal), in a state of supplying a predetermined voltage from the power supply unit, and the control unit calculates a resistance value of the piezoelectric element from a voltage value obtained by the measurement of the measuring unit, and determines, whether or not degradation has occurred in the piezoelectric element based on the calculated resistance value.