Auxiliary Capacitor Circuit for Stray Capacitance Compensation
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Solution Overview
Problem
Intraoral moisture measuring instruments using electrostatic capacity sensors face reduced measurement accuracy due to stray capacitance generated between the human body and the instrument when held by hand.
Innovation Solution
An electrostatic capacity sensor with a sensor unit comprising a first and second electrode forming a capacitor, connected to an electrostatic capacity detection circuit that includes a charge and discharge circuit, a control circuit, and an auxiliary capacity circuit with parallel-connected auxiliary capacitors to reduce stray capacitance influence, integrated within a handheld housing for accurate moisture content measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the intraoral moisture measuring instrument is held by hand for use, then the instrument can be conveniently operated, but stray capacitance is generated between the human body and the instrument causing measurement accuracy to decrease
Solution Approach 1:
The patent introduces an auxiliary capacity circuit as an intermediary component between the sensor unit and the detection circuit. This auxiliary capacity circuit, comprising auxiliary capacitors connected in parallel with the sensor capacitor, acts as a mediator to compensate for the stray capacitance effects. The auxiliary capacity circuit provides a known capacitance value that can be used to calculate and eliminate the influence of stray capacitance from the measurement, thereby maintaining measurement precision while allowing handheld operation.
Solution Approach 2:
The patent changes the electrical parameters of the measurement system by introducing auxiliary capacitors with specific capacitance values. By adjusting the capacitance parameters in the auxiliary capacity circuit, the system compensates for the stray capacitance introduced during handheld use. The control circuit adjusts the charging and discharging characteristics based on the auxiliary capacitor values, enabling the system to maintain accurate measurements despite the presence of stray capacitance from the human body.
2Adaptability or versatility
If an electrostatic capacity sensor is used to detect moisture content, then the measurement can be performed non-invasively, but stray capacitance from the human body interferes with the detection accuracy
Solution Approach 1:
The auxiliary capacity circuit serves as an intermediary that isolates the sensor unit from the stray capacitance effects. By providing a known capacitance reference through the auxiliary capacitors, the system can differentiate between the capacitance changes caused by moisture content and those caused by stray capacitance from the human body, maintaining non-invasive measurement capability while improving accuracy.
Solution Approach 2:
The control circuit implements feedback by monitoring the charging and discharging characteristics of the capacitor and using the auxiliary capacity information to compensate for stray capacitance effects. The system continuously adjusts the measurement calculations based on the auxiliary capacitor values, enabling accurate moisture content detection despite the interfering stray capacitance from the human body.
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
The solution effectively minimizes the impact of stray capacitance, enhancing the accuracy of electrostatic capacity detection and allowing for precise measurement of moisture content in the oral cavity.
Implementation Method 1
an auxiliary capacity circuit that has at least one of a first auxiliary capacitor connected to the first electrode in parallel with the capacitor and a second auxiliary capacitor connected to the second electrode in parallel with the capacitor
Data Source
AI summary
There are provided an electrostatic capacity sensor and a measuring instrument that can reduce influence of a stray capacitance on detection of an electrostatic capacity. An electrostatic capacity sensor includes a sensor unit having a first electrode and a second electrode constituting a capacitor, and an electrostatic capacity detection circuit that is connected to the sensor unit. The electrostatic capacity detection circuit includes a charge and discharge circuit that is connected to the first electrode and the second electrode to charge and discharge the capacitor, a control circuit that controls the charge and discharge circuit such that the capacitor repeats charge and discharge, and an auxiliary capacity circuit that has at least one of a first auxiliary capacitor that is connected to the first electrode in parallel with the capacitor and a second auxiliary capacitor that is connected to the second electrode in parallel with the capacitor.