Reflected Light Touch Sensing With Adaptive Threshold Calibration
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Solution Overview
Problem
Existing touch sensors in industrial instruments face reliability issues due to tolerance stack-ups and product-to-product variations, leading to inconsistent button presses and data entry errors in high humidity and temperature environments.
Innovation Solution
An adaptive reflected light touch sensor system that includes an emitter, a sensor to measure light amplitude, and a processor board to calculate a moving average and assert threshold, allowing for independent configuration and consistent button press detection across multiple sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard calibration routines are used with fixed distance and intensity standards, then the calibration process is simple, but tolerance stack-ups and product-to-product variations introduce errors in button press detection
Solution Approach 1:
The patent implements dynamic threshold adjustment where the assert threshold is not fixed but adapts based on measured reflected light amplitude. The system calculates a moving average of reflected light amplitude and dynamically sets the assert threshold as a percentage above this average, allowing the button press detection threshold to automatically compensate for manufacturing variations and environmental changes.
Solution Approach 2:
The system changes the detection parameter from a fixed absolute light amplitude threshold to a relative threshold based on moving average. By calculating the moving average of reflected light amplitude and setting the assert threshold dynamically (e.g., 10% above average), the system adapts to product-to-product variations and tolerance stack-ups without requiring recalibration.
2Reliability
If custom configurations are implemented for each product to improve reliability, then button press consistency improves, but manufacturing cost increases and additional defects may be introduced
Solution Approach 1:
The touch sensor system performs self-configuration by automatically calculating the moving average of reflected light amplitude and dynamically setting its own assert threshold. This self-adjusting capability eliminates the need for custom manual configurations for each product, achieving consistent button press detection across all units without increasing manufacturing complexity.
Solution Approach 2:
The system implements feedback by continuously measuring reflected light amplitude, calculating a moving average, and using this information to dynamically adjust the assert threshold. This closed-loop approach ensures reliable button press detection adapts to each unit's characteristics automatically, achieving consistency without custom manufacturing processes.
3Device complexity
If fixed thresholds are used for button press detection, then the detection logic is simple, but environmental variations cause inconsistent detection across different operating conditions
Solution Approach 1:
The assert threshold transitions from a static fixed value to a dynamic value that adapts to environmental conditions. By calculating the moving average of reflected light amplitude and setting the threshold as a percentage above this average, the system automatically adjusts to environmental variations such as temperature changes and humidity while maintaining simple detection logic.
Solution Approach 2:
The detection threshold parameter changes from a fixed absolute value to a relative value based on the moving average of reflected light. This parameter transformation allows the system to adapt to environmental variations while keeping the detection algorithm computationally simple, requiring only basic arithmetic operations.
4Ease of operation
If calibration is performed with standard distance and intensity, then the calibration setup is straightforward, but tolerance stack-ups cause data entry errors and delays
Solution Approach 1:
The system performs automatic self-calibration by measuring the reflected light amplitude from the button surface and calculating a moving average to establish the assert threshold. This eliminates the need for manual calibration with standard distance and intensity references, maintaining ease of operation while preventing data entry errors caused by tolerance stack-ups.
Solution Approach 2:
The system performs preliminary measurement of the reflected light amplitude during initialization or setup, calculating the moving average and establishing the assert threshold before actual button press detection begins. This preliminary action compensates for tolerance variations in advance, preventing data entry errors and improving productivity without requiring complex calibration procedures.
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 provides reliable and consistent data input by adapting to environmental variations and product tolerances, reducing errors and delays in data entry.
Implementation Method 1
an emitter that emits light in a direction that reflects the light, a sensor positioned to measure a light amplitude of the reflected light
Data Source
AI summary
An adaptive reflected light touch sensor (100, 400) is provided. The adaptive reflected light touch sensor (100, 400) includes an emitter (110) that emits light in a direction that reflects the light (RLI, RLO), a sensor (120, 410) positioned to measure a light amplitude of the reflected light (RLI, RLO), a processor board (150) coupled to the sensor (120, 410), the processor board (150) being configured to calculate a moving average of the measured light amplitude of the reflected light (RLI, RLO) and calculate an assert threshold.