Touch Switch Detection Using Microcontroller Capacitive Sensing
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Solution Overview
Problem
Conventional electrical cookers with mechanical buttons face issues like elasticity fatigue and high temperature-induced shape changes, while touch switches are complex and costly to design and implement, and existing control systems are prone to errors and instability due to software inaccuracies and complex procedures.
Innovation Solution
A micro-controller based apparatus with a RC oscillator, touch switches, analog switches, and counters that generate and process transition signals to detect touch switch states, allowing for software-controlled ON/OFF switching and simplified peripheral device integration, using a panel control unit to transmit signals and control LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical buttons are used as input devices, then the structure is simple and easy to manufacture, but they suffer from elasticity fatigue and shape changes due to high temperature
Solution Approach 1:
The patent replaces mechanical buttons with touch switches that detect touch through electrical field changes. The touch switch includes a touch-sensitive electrode that detects capacitance changes when touched, eliminating mechanical moving parts and improving reliability under high temperature conditions while maintaining manufacturing simplicity.
2Reliability
If touch switches are used to replace mechanical buttons, then reliability is improved, but the design becomes complicated and costly with many additional electric devices
Solution Approach 1:
The patent merges the touch switch detection function with the existing microcontroller by using the microcontroller's internal capacitive sensing capability. The touch-sensitive electrode is directly connected to the microcontroller, eliminating the need for separate detection circuits, analog switches, and RC oscillators, thus reducing device complexity while maintaining reliability.
Solution Approach 2:
The microcontroller is designed to perform multiple functions including touch detection, timing, and control operations. The same microcontroller that controls the cooker also detects touch inputs through its internal capacitive sensing, eliminating the need for dedicated touch detection hardware and reducing overall system complexity.
3Device complexity
If software is used to detect touch switch states with RC oscillator, then hardware complexity is reduced, but timing accuracy is affected by instruction execution delays
Solution Approach 1:
The patent replaces the RC oscillator-based timing method with a counter-based timing system that uses the microcontroller's internal clock. The counter counts clock cycles during the touch detection period, providing accurate timing measurement without the frequency drift and timing errors associated with RC oscillators and software instruction delays.
4Adaptability or versatility
If multiple electric devices are combined in the control system, then functionality is enhanced, but the overall system cost increases
Solution Approach 1:
The microcontroller is designed to perform multiple functions including touch detection, timing, power control, and display management. By integrating these functions into a single microcontroller unit, the patent reduces the number of separate components needed, thereby lowering system cost while maintaining enhanced functionality.
Solution Approach 2:
The patent combines the touch detection circuitry, timing functions, and control logic into a single integrated microcontroller unit. This merging of functions eliminates the need for separate hardware components for each function, reducing both device complexity and overall system cost while maintaining versatility.
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 solution provides a stable, cost-effective, and accurate method for detecting touch switch states, reducing complexity and errors, and enabling faster detection times, improving user experience and reducing the overall cost of electrical cooker control systems.
Implementation Method 1
a RC oscillator for generating a reference clock
Implementation Method 2
a plurality of touch switches for generating a transition signal indicating one of the touch switches being touched by human beings
Data Source
AI summary
The present invention provides a micro-control unit a RC oscillator for generating a reference clock, a plurality of touch switches for generating a transition signal indicating one of the touch switches being touched by human beings, a plurality of analog switches coupled to the touch switches for controlling transmission of the transition signal and a plurality of counters for counting time, all of the counters stop counting when one of the counters overflows and content of all counters being read, wherein ON/OFF of the analog switches controlled by a software.