Touch Sensor Impedance Adjustment for Submersion-Safe Detection
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Solution Overview
Problem
Sensors such as touch sensors and capacitive sensors face sensitivity variations due to changes in environmental conditions like power voltage, ambient temperature, and humidity, leading to impaired functionality, especially when the touch pad is submerged or when specific channels are in contact with a touch object.
Innovation Solution
An automatic impedance adjuster system that includes a pulse signal generating part, signal processing channels, and a controller to detect changes in environmental conditions and adjust impedance by controlling pulse width or delay values, ensuring proper sensor operation across varying environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If impedance adjustment is performed when specific channels are in contact with a touch object, then sensor sensitivity can be maintained under normal conditions, but false detection occurs and reliability deteriorates when the touch pad is submerged or all channels are contacted
Solution Approach 1:
The system uses feedback from multiple channels to determine whether to perform impedance adjustment. The controller monitors contact states across all channels and only adjusts impedance when specific conditions are met (not all channels contacted and contact duration exceeds threshold), preventing false adjustments that would occur when the touch pad is submerged or fully contacted.
Solution Approach 2:
The impedance adjustment mechanism is made dynamic and conditional rather than continuous. The system adapts its behavior based on real-time channel contact states, performing adjustment only when environmental conditions suggest it's appropriate (partial contact state with sufficient duration), and avoiding adjustment when conditions indicate submersion or full contact.
2Measurement precision
If automatic impedance adjustment is continuously performed, then sensor sensitivity is maintained, but false detection occurs due to inappropriate adjustment timing
Solution Approach 1:
The system performs preliminary checks before impedance adjustment by monitoring channel contact states and contact duration. It determines whether the current environment is appropriate for adjustment (partial contact with sufficient duration) before executing the adjustment, preventing premature or inappropriate adjustments that would cause false detection.
Solution Approach 2:
Instead of continuous adjustment, the system performs impedance adjustment periodically based on detected contact patterns. It monitors channels over time, and only triggers adjustment when specific periodic conditions are met (contact duration threshold exceeded in partial contact state), creating a rhythm of adjustment that avoids false detection.
3Speed
If impedance adjustment is performed based on single channel contact, then adjustment responsiveness is improved, but false detection occurs when all channels are simultaneously contacted
Solution Approach 1:
The system uses multiple channels serving dual purposes: individual channels detect local contact for responsiveness, while the collective state of all channels determines whether impedance adjustment should occur. This multi-functional use of channels allows the system to respond quickly to contact events while simultaneously assessing the global environment to avoid false adjustments.
Solution Approach 2:
The system merges individual channel contact detection with global contact state assessment. It combines information from all channels to determine the overall contact situation, and only performs impedance adjustment when the combined state indicates partial contact with sufficient duration, merging local responsiveness with global 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
The system effectively maintains sensor sensitivity and reliability by automatically adjusting impedance in response to environmental changes, preventing malfunctions and ensuring consistent touch sensor performance.
Implementation Method 1
a touch sensor which detects in contact with an object by sensing an impedance change depending on whether the object is contact with a touch pad or not
Implementation Method 2
a capacitive sensor which detects a position of an object by sensing a capacitance change varied by a user's adjustment
Data Source
AI summary
Provided are an automatic impedance adjuster and a control method thereof. The automatic impedance adjuster includes a specific channel for checking an operating environment. When an operation signal of the specific channel is detected or operation signals of all the channels are detected, the automatic impedance adjustment operation is performed to prevent malfunction of the impedance adjustment operation. In addition, malfunction of a touch sensor due to variation of the operating environment can be prevented to improve operating reliability of the touch sensor.