Electrostatic Capacitive Sensor Contact and Pressing Detection
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Solution Overview
Problem
Existing input state detection devices using electrostatic capacitive sensors face instability in detecting pressing force due to changes in potential or electric current, affecting the reliability of contact and pressing detection.
Innovation Solution
A constant-voltage power supply device is used in conjunction with an electrostatic capacitive sensor, where the detector is connected in series, and a state switching switch alternates between two states to reliably differentiate between contact and pressing states by altering the connection between the electrodes, allowing for precise detection of pressing force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a detector is connected to monitor potential or electric current changes in an electrostatic capacitive sensor, then contact and pressing of an object can be detected, but the detected potential or electric current becomes unstable depending on the magnitude of pressing force
Solution Approach 1:
The detection process is segmented into two distinct phases by using a state switching switch: a first state for detecting contact between the object and the sensor, and a second state for detecting pressing force. This segmentation allows each detection phase to use optimized circuit configurations, improving both precision and reliability for each specific detection task.
Solution Approach 2:
The circuit configuration is made dynamic through the state switching switch that alternates between connecting the voltage application terminal to the first electrode (first state) and to the second electrode (second state). This dynamic switching enables the system to adapt its detection mode based on whether contact or pressing force is being measured, resolving the instability issue.
2Measurement precision
If the detector monitors potential or electric current changes in the electrostatic capacitive sensor, then pressing force can be detected, but the detection reliability decreases due to potential changes
Solution Approach 1:
The state switching switch periodically alternates between the first state and the second state, enabling periodic detection of contact and pressing force. This periodic action allows the system to sample data at optimal moments for each measurement type, improving detection reliability by avoiding continuous monitoring during unstable transitions.
Solution Approach 2:
The system performs preliminary detection in the first state to confirm object contact before proceeding to pressing force detection in the second state. This preliminary action ensures that pressing force is only measured when an object is actually in contact with the sensor, improving the reliability of pressing force detection.
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
This configuration provides stable and reliable detection of contact and pressing states, enabling early detection of pressing and changes in pressing force, reducing energy consumption and minimizing switch operations.
Implementation Method 1
an electrostatic capacitive sensor having a first electrode attached to a substrate, a second electrode located on a side of an electrically conductive object to be contacted, and a dielectric layer placed between the first electrode and the second electrode
Implementation Method 2
detecting potential of the detection terminal or an electric current flowing from the detection terminal which changes with electrostatic capacitance of the electrostatic capacitive sensor and electrostatic capacitance of the object
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
Provided is an input state detection device capable of reliably detecting contact and pressing of an object. A state switching switch (50) can switch a first state in which a voltage application terminal (21) of a constant-voltage power supply device (20, 220) is connected to a side of a first electrode (11) and a detection terminal (31, 231) of a detector (30, 230) is connected to a side of second electrodes (12a to 12h), and a second state in which the voltage application terminal (21, 221) of the constant-voltage power supply device (20, 220) is connected to the side of the second electrodes (12a to 12h) and the detection terminal (31, 231) of the detector (30, 230) is connected to the side of the first electrode (11). An input detector (70, 170, 270) detects whether the object is in a non-contact state or in a contact but not pressing state with respect to a surface on the side of the second electrodes (12a to 12h) based on a value detected by the detector (30, 230) with the state switching switch (50) in the first state, and also detects whether the object is in the contact but not pressing state or in a pressing state with respect to the surface on the side of the second electrodes (12a to 12h) based on a value detected by the detector (30, 230) with the state switching switch (50) in the second state.