Capacitive Touch Pad Circuit for Water-Induced False Touch Rejection
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Solution Overview
Problem
Conventional touch pads on electronic devices are not waterproof, leading to misjudgments by IC chips when water interacts with the touch pads, resulting in excessive energy consumption and unnecessary machine operations.
Innovation Solution
A touch system that applies equipotentials or division voltages to erase the capacitance effect caused by ion-contained liquids, using a circuit board with touch pads, a control chip, and an insulation board to determine the validity of a touch by generating voltage oscillation waves and judging the division voltage, thereby distinguishing between human and water-induced touches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional touch pads are used without waterproofing, then the touch detection function is simple and cost-effective, but water drops cause false touches leading to excessive energy consumption and unnecessary operations
Solution Approach 1:
The system performs preliminary detection by measuring capacitance values before executing touch operations. The control chip detects capacitance changes on the circuit board, compares them against threshold values, and only triggers operations when valid touch patterns are confirmed, preventing water-induced false triggers from consuming energy
Solution Approach 2:
The system implements feedback mechanisms where the control chip continuously monitors capacitance values from multiple touch pads, compares detected values against predetermined thresholds, and adjusts operation execution based on whether the detected capacitance patterns match valid touch signatures, thereby eliminating false operations and reducing unnecessary energy consumption
2Reliability
If waterproofing measures are added to touch pads, then water-induced false touches are prevented, but the device structure becomes more complex
Solution Approach 1:
The patent introduces an intermediary detection layer using the circuit board's inherent capacitance properties. The control chip acts as a mediator that interprets capacitance changes to distinguish between water contact and human touch, preventing the need for complex physical waterproofing barriers while maintaining reliability
Solution Approach 2:
The system replaces mechanical waterproofing structures with an electrical detection and discrimination mechanism. Instead of using physical barriers to prevent water contact, the invention uses capacitance sensing and software-based touch validation to distinguish water from human touch, significantly reducing structural complexity
3Ease of operation
If capacitance-based touch detection is used, then touch sensitivity is high, but ion-contained liquids create capacitance effects that cause misjudgment
Solution Approach 1:
The system uses excessive detection by measuring capacitance values from multiple touch pads simultaneously and comparing each against threshold values. By detecting capacitance changes across the entire circuit board rather than relying on a single touch point, the system can identify patterns that distinguish valid human touch from water contact, maintaining sensitivity while improving judgment accuracy
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 prevents false triggers by erasing the capacitance effect of accidental water drops and ensures valid touch detection, enhancing the operability of electronic devices by avoiding mis-touched commands.
Implementation Method 1
a capacitance effect between the conductive board body and the touch portion of one of the touch pads is fainted by the work voltage. Then, the voltage oscillation wave is applied to erase the capacitance effect
Data Source
AI summary
A touch system includes a circuit board, touch pads, a control chip and an insulation board. The circuit board has a conductive board body including configuration regions. The touch pads is spaced from the configuration regions by the conductive board body. Each touch pad includes at least one touch portion. The control chip includes a multiplex module coupling the touch pads and an oscillation control module coupling the conductive board body. The oscillation control module conducts alternately the multiplex module and every touch portions to utilize a work voltage for generating a voltage oscillation wave respective to each conducted touch portion. The voltage oscillation wave is transmitted to the conductive board body. When an ion-contained liquid is on the insulation board by covering partly the conductive board body and the touch portion, a capacitance effect therebetween is forming by the work voltage, but further erased by the voltage oscillation wave.