Force Sensing via Air Pressure and Flow Measurements
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Solution Overview
Problem
Existing force sensing technologies in devices like smartphones and tablets face challenges in accurately determining force applied to a display surface due to unpredictable air flow and pressure changes, especially when the device is not completely sealed, leading to potential deformation or leakage of seals.
Innovation Solution
A device employing a combination of pressure and air flow sensors, along with a processor, to measure air pressure within an interior volume and air flow between the interior and exterior, allowing for precise determination of force applied to a display surface, and also capable of detecting damaged seals by comparing measured air pressure and flow relationships.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a device uses a completely sealed interior volume for force sensing, then measurement precision improves, but reliability deteriorates due to seal deformation or leakage
Solution Approach 1:
The sealed interior volume is divided into multiple sealed cavities, each with its own pressure sensor. This segmentation allows the system to maintain measurement precision while reducing the stress on individual seals, as each cavity is smaller and less prone to deformation or leakage.
Solution Approach 2:
The device performs preliminary calibration to establish baseline pressure values when no force is applied. This preliminary action allows the system to compensate for minor seal deformations by comparing current pressure readings against the calibrated baseline, maintaining measurement precision without requiring perfect seal integrity.
2Measurement precision
If a device uses capacitive force sensors, then force sensing capability is achieved, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex capacitive force sensors with a simpler system using pressure sensors and air flow sensors. By measuring pressure changes and air flow patterns in response to applied force, the system achieves force sensing capability while reducing device complexity and cost.
Solution Approach 2:
The device uses pneumatic principles by introducing air flow through controlled openings and measuring pressure changes in response to applied force. This pneumatic approach simplifies the sensor system compared to capacitive sensors, as it uses readily available pressure sensors and leverages the compressibility of air to translate force into measurable pressure variations.
3Reliability
If a device has ports connecting interior volume to exterior, then reliability improves by preventing seal damage, but measurement precision deteriorates due to unpredictable air flow
Solution Approach 1:
The device uses air flow sensors to monitor air flow through the ports and incorporates this information as feedback into the force calculation. By measuring both pressure changes and air flow patterns, the system can distinguish between pressure changes caused by applied force versus those caused by air flow, thereby maintaining measurement precision while allowing ports to protect seal integrity.
Solution Approach 2:
The air flow acts as an intermediary that connects the interior pressure system to the exterior environment while providing measurable information. By introducing controlled air flow through ports and measuring it with air flow sensors, the system maintains seal protection while using the air flow measurements to compensate for and correct force sensing 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
This solution provides accurate force sensing at a lower cost compared to capacitive or resistive force sensors, while also enabling the detection of damaged seals through notifications, thus enhancing the reliability and durability of mobile electronic devices.
Implementation Method 1
a pressure sensor configured to measure an air pressure within the interior volume
Implementation Method 2
an air flow sensor configured to measure an air flow through the port
Data Source
AI summary
A mobile communication device includes a housing defining an interior volume and a port connecting the interior volume to an environment exterior to the device. The mobile communication device also includes a display viewable through a surface of the housing, a pressure sensor configured to measure an air pressure within the interior volume, an air flow sensor configured to measure an air flow through the port, and a processor. The processor is configured to determine an amount of force applied to the housing using a measurement of the air pressure by the pressure sensor and a measurement of the air flow by the air flow sensor.