Press Sensor Bottom Wall Slit Design for Thin Housing Sensitivity
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Solution Overview
Problem
Existing press sensors struggle to detect deformation in housings with thin side walls effectively due to reduced sensor size and adhesiveness, leading to low output and sensitivity.
Innovation Solution
The arrangement of press sensors on the bottom wall of the housing, with a slit dividing it into regions that allow for greater displacement and sensitivity, utilizing piezoelectric films made of polylactic acid to detect shear distortion, and optionally using a filler softer than the housing material to enhance sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the sensor is disposed on a thin side wall of the housing, then the sensor size must be reduced to fit the thin wall, but this reduces the sensor output and detection sensitivity
Solution Approach 1:
The sensor is relocated from the side wall to the bottom wall of the housing, changing the spatial dimension where the sensor is disposed. This allows the sensor to be positioned on a surface with greater available area (the bottom wall) while still detecting side wall deformation through the transmission of mechanical stress through the housing structure.
Solution Approach 2:
The bottom wall is divided into multiple regions (first region, second region, third region) with different displacement characteristics. The sensor is positioned to detect displacement in the first region, which is specifically designed to have greater displacement in response to side wall pressing operations, thereby enhancing detection sensitivity.
2Area of stationary object
If the sensor area adhered to the housing is reduced due to thin wall constraints, then the sensor size must be smaller, but this reduces the adhesiveness of the sensor to the housing
Solution Approach 1:
The sensor is moved to the bottom wall where a larger adhered area is available, directly resolving the constraint of limited surface area on thin side walls. This provides sufficient bonding area for reliable sensor attachment while maintaining the ability to detect side wall deformation.
3Measurement precision
If a slit is introduced to increase displacement sensitivity, then the detection sensitivity is improved, but the structural strength of the housing may be reduced
Solution Approach 1:
The bottom wall is segmented into multiple regions by slits, creating distinct zones with different mechanical properties. The first region is designed to have greater displacement capability for enhanced sensor detection, while the second and third regions maintain structural integrity. This segmentation allows the housing to simultaneously achieve both high detection sensitivity and adequate structural strength.
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 configuration enables the detection of deformation with improved sensitivity and durability, even in thin-walled housings, by amplifying the displacement of the side wall's pressing force onto the bottom wall regions, allowing for precise detection of shear distortion.
Implementation Method 1
the press sensor includes a piezoelectric film that detects shear distortion
Data Source
AI summary
A housing includes a side wall that includes a button region that receives a pressing operation and a bottom wall that cooperates with the side wall to define a cavity. The bottom wall has first and second regions in which the first region is more easily displaced in response to the pressing operation than the second region. A press sensor is disposed on the bottom wall in the cavity and extends across portions of the first and second regions. A slit is located in the bottom wall between the side wall and the second region and causes the first region to be more easily displaced in response to the pressing operation than the second region.