Capacitance detection sensor, capacitance detection sensor module and state determination method using capacitance detection sensor
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Solution Overview
Problem
Variations in conductive rubber characteristics can lead to inaccurate detection of pressure application, causing erroneous separation detection of human body parts from conductive rubber.
Innovation Solution
A capacitance detection sensor module measures capacitances between reference and first electrodes, and reference and second electrodes during distinct detection periods, using an electrostatic shielding member to improve state determination accuracy independently of conductive characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electric resistance value measurement is used to detect pressure on conductive rubber, then pressure detection is possible, but detection accuracy deteriorates due to variations in conductive rubber characteristics
Solution Approach 1:
The patent introduces a capacitance detection mechanism as an intermediary between the object and the conductive rubber sensor. By measuring capacitance changes caused by objects approaching or contacting the sensor surface, the system detects pressure and proximity without relying on conductive rubber's electrical resistance characteristics, thus eliminating the reliability issues associated with material variations
Solution Approach 2:
The patent replaces the electrical resistance-based detection system with a capacitance-based detection system. This substitution transitions from measuring electrical resistance changes in conductive rubber to measuring capacitance changes in the electric field, thereby avoiding the problems caused by conductive rubber's variable electrical characteristics while maintaining pressure detection capability
2Measurement precision
If capacitance detection is used to detect object proximity, then proximity detection accuracy is improved, but measurement errors occur due to electrostatic interactions
Solution Approach 1:
The patent introduces a ground electrode as an intermediary element positioned between the detection electrode and the object. This ground electrode acts as a shield that intercepts and dissipates electrostatic charges from approaching objects, preventing direct electrostatic interaction between the detection electrode and the object, thus eliminating measurement errors while preserving proximity detection accuracy
Solution Approach 2:
The patent converts the harmful electrostatic interaction into a beneficial shielding effect by introducing a grounded electrode. The electrostatic charges that would otherwise cause measurement errors are redirected to the ground electrode, which safely dissipates them. This transforms the potentially harmful electrostatic field into a protective shielding mechanism that improves measurement reliability
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
Enhances the accuracy of detecting object proximity and pressure on the sensor module by stabilizing state determination and reducing measurement errors due to electrostatic interactions.
Implementation Method 1
an electrostatic shielding member arranged in a ground state between the reference electrode and the first electrode in a direction parallel to the surface of the base material
Implementation Method 2
a capacitance C1 between the reference electrode and the first electrode is measured in the first detection period in which a voltage is applied between the reference electrode and the first electrode
Data Source
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AI summary
The present invention provides a capacitance detection sensor capable of improving the detection accuracy of the presence or absence of proximity of an object such as a human body and pressure received from the object. A pair of first electrodes 111, 112 is arranged in a state being separated in a direction parallel to a contact surface 102 of a base material 10 made of a dielectric and being at least partially in contact with the base material 10. A pair of second electrodes 121, 122 is arranged in a state of overlapping at least one of the pair of first electrodes and sandwiching the base material 10 at a position farther from the contact surface 102 of the base material 10 than the pair of first electrodes 111 and 112 in a direction perpendicular to the contact surface 102 of the base material 10. The proximity state of an object Q with respect to the contact surface 102 of the base material 10 is detected according to the measurement result of the capacitance C1 between the pair of first electrodes 111 and 112. The pressure acting on the base material 10 from the object Q in contact with the contact surface 102 of the base material 10 is detected according to the measurement result of the capacitance C2 between the pair of second electrodes 121 and 122.