Force-Sensitive Button Thermal Compensation for Reliable Activation
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Solution Overview
Problem
Force-sensitive buttons in electronic devices experience degraded performance due to thermal drift caused by temperature differentials between the user's object and the button, leading to false positive button presses or inconsistent activation requirements.
Innovation Solution
Incorporating a temperature sensor to measure temperature changes and applying thermal compensation by determining a compensated gap based on the measured capacitance of a capacitive-gap force sensor, using a thermal transfer function to estimate and subtract thermal effects, thereby adjusting the force measurement to accurately reflect user input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a force sensor is used to replace a mechanical switch, then the button can provide continuous force measurement capability, but thermal drift causes degraded performance including false positives and inconsistent activation thresholds
Solution Approach 1:
The patent implements feedback by continuously monitoring temperature via a temperature sensor and using this information to dynamically adjust force measurement readings. The system measures temperature, determines thermal drift based on the temperature change, and compensates the force sensor output accordingly, creating a closed-loop system that eliminates thermal drift effects and maintains reliable button activation thresholds
Solution Approach 2:
The patent introduces temperature as an intermediary variable to understand and compensate for thermal drift effects. By measuring temperature change and using it to determine the magnitude of thermal drift, the system mediates between the temperature environment and the force sensor output, allowing accurate force measurement despite thermal conditions
2Measurement precision
If thermal compensation is applied continuously, then measurement accuracy is improved, but energy consumption increases due to continuous temperature sensing and compensation calculations
Solution Approach 1:
The patent applies periodic action by enabling thermal compensation only during specific conditions - when a button press is detected or when temperature changes exceed a threshold. The system monitors temperature continuously but performs compensation calculations selectively, rather than continuously, reducing energy consumption while maintaining measurement accuracy when needed
Solution Approach 2:
The patent uses partial action by applying thermal compensation only to the extent necessary - when temperature change indicates significant thermal drift. The system determines compensation based on actual temperature change magnitude and applies it only when needed, rather than always applying full compensation, optimizing the balance between accuracy and energy usage
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 approach reduces false positives and ensures consistent performance by accurately differentiating between user-applied force and thermal drift, maintaining reliable button activation thresholds.
Implementation Method 1
a force sensor (e.g., capacitive gap sensor) configured to measure an amount of force applied to the force-sensitive button
Implementation Method 2
a temperature sensor configured to measure a temperature associated with the force sensor
Implementation Method 3
determining an estimated gap associated with a temperature change introduced into the force-sensitive button by the object touching the surface of the force-sensitive button based on the temperature associated with the force sensor (e.g., based on a thermal transfer function)
Data Source
AI summary
Thermal compensation can be applied to force measurements of a force-sensitive button. A temperature differential between an object and the force-sensitive button can result in changes in the reconstructed force by the force sensor due to thermal effects rather than actual user force, which in turn can result in degraded performance of the force sensor (e.g., false positive or inconsistent activation force). In some examples, a force-sensitive button can include a force sensor configured to measure an amount of force applied to the force-sensitive button, and a temperature sensor configured to measure a temperature associated with the force sensor. The measured temperature can be used to compensate the amount of force measured by the force sensor based on the temperature associated with the force sensor. In some examples, the thermal compensation can be applied when an object is detected contacting the force-sensitive button (i.e., when rapid temperature differentials can occur).