Infrared Touch Switch Threshold Calibration for Stable Sensitivity
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Solution Overview
Problem
Existing infrared touch switches in field devices face challenges with sensitivity adjustment due to hardware characteristics, reflectance differences, and circuit errors, leading to inconsistent touch detection and operational feel.
Innovation Solution
A sensitivity adjustment device that calculates a threshold value based on the maximum and minimum voltage levels of A/D converter output, eliminating the need for manual setting and storage of threshold values, and automatically adjusts sensitivity by comparing the signal level with calculated thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual sensitivity adjustment with fixed threshold values is used, then touch detection sensitivity can be adjusted, but hardware characteristics and reflectance differences cause inconsistent operational feel across different devices
Solution Approach 1:
The patent dynamically changes the threshold parameter based on actual A/D converter output characteristics. Instead of using fixed threshold values, the system automatically determines optimal thresholds by analyzing the statistical distribution of A/D output data, adapting to hardware variations and ensuring consistent touch detection sensitivity across different devices.
Solution Approach 2:
The system performs self-adjustment by automatically analyzing its own A/D converter output characteristics and determining appropriate threshold values without external intervention. The microcontroller autonomously calibrates the touch detection sensitivity by processing sampled data and setting thresholds based on observed signal distributions.
2Ease of operation
If fixed threshold values are stored in nonvolatile memory, then sensitivity adjustment is possible, but additional components and manufacturing steps are required
Solution Approach 1:
The patent extracts the threshold value determination function from external storage components and implements it directly in the microcontroller's processing logic. By calculating thresholds programmatically from A/D output data rather than storing them in nonvolatile memory, the system eliminates the need for separate threshold storage components and associated manufacturing steps.
Solution Approach 2:
The microcontroller serves multiple functions: it controls the A/D converter, processes the output data, determines optimal threshold values, and controls the display. This multi-functional approach consolidates what would traditionally require separate components (threshold storage, threshold determination logic, control functions) into a single integrated processing unit.
3Ease of operation
If manual threshold setting is performed, then sensitivity can be adjusted, but time-consuming calibration processes are required
Solution Approach 1:
The system performs preliminary automatic calibration by analyzing A/D converter output characteristics and determining optimal threshold values during the initial operation phase. This preliminary action eliminates the need for time-consuming manual calibration processes, as the thresholds are automatically optimized based on actual device characteristics before normal operation begins.
Solution Approach 2:
The system performs self-calibration by automatically analyzing its own output characteristics and determining appropriate threshold values without external intervention. The microcontroller autonomously processes sampled A/D data, identifies signal distribution patterns, and sets optimal thresholds, eliminating the need for manual calibration operations.
4Reliability
If sensitivity adjustment parameters are stored in nonvolatile memory, then touch detection sensitivity can be maintained, but manufacturing costs increase
Solution Approach 1:
The patent extracts the sensitivity parameter storage function from nonvolatile memory and implements it in volatile memory or register-based storage within the microcontroller. By determining thresholds programmatically and storing them in faster, cheaper memory resources already present in the microcontroller, the system eliminates the need for separate nonvolatile memory components dedicated to parameter storage.
Solution Approach 2:
The microcontroller's internal memory resources are used for multiple purposes: storing program code, processing A/D data, and holding threshold values. This multi-functional use of existing memory resources eliminates the need for additional nonvolatile memory components, reducing manufacturing costs while maintaining the ability to store and retrieve sensitivity parameters.
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 stabilizes touch detection sensitivity, reduces component count and manufacturing costs, and ensures consistent operational feel by automatically calculating and updating threshold values, independent of hardware characteristics and reflectance variations.
Implementation Method 1
a light receiver 6 which receives the reflected light and converts the reflected light into an analog electrical signal
Data Source
AI summary
A sensitivity adjustment device may include: a light receiver configured to receive a reflected light that has been emitted from a light emitting unit and reflected by a reflector, the light receiver being configured to convert the reflected light into an analog electrical signal; an A/D converter configured to convert the analog electrical signal into a digital signal; a threshold value calculator configured to calculate a threshold value with reference to a voltage level of the digital signal that has been sequentially converted and output by the A/D converter; and a determination unit configured to compare a high voltage level of the digital signal with the threshold value.