Capacitive Input Sensing with Switched Electrodes for Press 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, making reliable contact and pressing detection challenging.
Innovation Solution
A constant-voltage power supply device is used in conjunction with an electrostatic capacitive sensor and a detector, with a state switching switch to alter the connection between the voltage application terminal and detection terminal, allowing for distinct detection of contact and pressing states by varying the electrostatic capacitance and current flow.
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: a first state for detecting contact (where the voltage application terminal is connected to the first electrode and detection terminal to the second electrode), and a second state for detecting pressing (where connections are reversed). This segmentation allows each detection mode to be optimized independently, resolving the contradiction between detection precision and stability by separating the detection functions into distinct operational states.
2Measurement precision
If the voltage application terminal is connected to the first electrode and detection terminal to the second electrode, then contact state can be detected, but pressing force magnitude cannot be reliably detected due to potential instability
Solution Approach 1:
The patent applies inversion by reversing the connection configuration when transitioning from contact detection to pressing detection. In the first state, voltage is applied to the first electrode and detected at the second electrode for contact detection. In the second state, the connections are inverted (voltage to second electrode, detection at first electrode) to enable reliable pressing force detection. This inversion resolves the contradiction by using opposite connection configurations for different detection purposes.
3Loss of information
If the detector monitors both potential and electric current changes, then comprehensive detection information can be obtained, but the detection system becomes more complex and less stable
Solution Approach 1:
The system uses periodic action by alternately switching between the first state and second state through a state switching switch. During each period, the system sequentially performs contact detection in the first state and pressing detection in the second state. This periodic switching allows comprehensive detection information to be obtained over time while maintaining system simplicity and stability, as only one detection configuration is active at any given moment.
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 enables reliable detection of non-contact, contact without pressing, and pressing states with improved stability and precision, allowing for early detection of pressing and changes in pressing force.
Implementation Method 1
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
AI summary
Provided is an input state detection device capable of reliably detecting contact and pressing of an object. A state switching switch can switch a first state in which a voltage application terminal of a constant-voltage power supply is connected to a side of a first electrode and a detection terminal of a detector is connected to a side of second electrodes, and a second state in which the voltage application terminal of the constant-voltage power supply is connected to the side of the second electrodes and the detection terminal of the detector is connected to the side of the first electrode. An input detector 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 based on a value detected by the detector with the state switching switch in the first state.