Capacitive Sensor Circuit With Reference Comparison and Capacitance Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Capacitive sensor devices face accuracy degradation due to manufacturing variations, leading to errors in detecting electrostatic capacity changes in capacitors, particularly in temperature-sensitive applications where wax-based dielectric elements melt and change capacitance.
Innovation Solution
A semiconductor device with a capacitive sensor circuit that includes a reference capacitive circuit, a determination circuit, and a correction capacitive circuit to accurately compare and adjust electrostatic capacities, using relay terminals to charge and discharge capacitors and apply designated electrostatic capacities, thereby enhancing detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reference capacitive circuit is used to compare electrostatic capacities, then detection accuracy is improved, but device complexity increases due to additional circuit components
Solution Approach 1:
The determination circuit merges the reference capacitive circuit and sensor capacitor comparison into a single integrated structure. Both capacitors are charged through shared charging circuits and their potentials are compared simultaneously, reducing the need for separate measurement systems while maintaining high detection accuracy.
Solution Approach 2:
The charging circuits serve multiple functions: they charge both the reference capacitive circuit and sensor capacitor, provide correction capacitance adjustment, and enable comparison operations. This multi-functionality reduces the overall number of components needed while improving measurement precision through the reference comparison mechanism.
2Measurement precision
If manufacturing variations are not compensated, then device complexity remains low, but measurement precision degrades due to errors in detecting electrostatic capacity changes
Solution Approach 1:
The correction capacitive circuit is configured in advance to compensate for manufacturing variations. By pre-setting the correction capacitance values and having the determination circuit automatically select appropriate correction amounts based on detected deviations, the system addresses measurement errors before they affect final detection accuracy, eliminating the need for complex post-manufacturing calibration procedures.
3Measurement precision
If relay terminals are used to supply charging current to both sensor capacitor and reference capacitive circuit, then measurement accuracy is improved through controlled charging, but device complexity increases due to additional switching components
Solution Approach 1:
The relay terminals serve multiple functions: they switch charging current to both the sensor capacitor and reference capacitive circuit, enable potential comparison operations, and facilitate correction capacitance application. This multi-functionality allows precise control of the charging process and comparison operations without requiring separate switching mechanisms for each function, thereby improving measurement accuracy while limiting the increase in device complexity.
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 ensures high accuracy in detecting electrostatic capacity changes by compensating for manufacturing variations and accurately determining temperature-related capacitance shifts, improving the reliability of temperature monitoring in capacitive sensor devices.
Implementation Method 1
a sensor capacitor with electrostatic capacity changing in response to a change in environment
Implementation Method 2
since the dielectric constant of the air is smaller than the dielectric constant of the wax, the electrostatic capacity in the sensor capacitor is reduced
Implementation Method 3
detects electrostatic capacity of the capacitor and determines whether or not the electrostatic capacity of the capacitor has changed by comparing magnitudes of potentials at the first relay terminal and the second relay terminal
Data Source
AI summary
The disclosure includes: an electrode pad connected between a capacitor that is a target of detection and a first node for externally connecting the capacitor; a reference capacitive circuit that has a reference electrostatic capacity and applies the reference electrostatic capacity to a second node; a determination circuit that includes first and second relay terminals, supplies a charging current from the first relay terminal to an electrode pad via the first node, supplies a charging current from the second relay terminal to the reference capacitive circuit via the second node, and subsequently detects electrostatic capacity of the capacitor and determines whether or not the electrostatic capacity of the capacitor has changed by comparing magnitudes of potentials at the first relay terminal and the second relay terminal; and a correction capacitive circuit that applies a designated electrostatic capacity to the first node and is capable of varying the electrostatic capacity.