Same-Layer Force Sensors for Accurate Pressure Detection
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Solution Overview
Problem
Existing electronic devices with force sensors disposed on different layers face challenges in accurately detecting pressure due to similar resistance changes caused by temperature and pressure, leading to increased thickness and manufacturing costs.
Innovation Solution
An electronic device with force sensors disposed on the same layer, where a first sensor detects pressure applied to a cover window, and a second sensor on the same layer detects the pressure with the aid of adhesive members to minimize deformation and enhance sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If force sensors are disposed on different layers, then temperature-induced resistance changes can be distinguished from pressure-induced changes, but the overall thickness of the electronic device increases and manufacturing costs increase
Solution Approach 1:
The patent merges multiple force sensors onto the same layer (e.g., same substrate or panel) rather than distributing them across different layers. This consolidation maintains the capability to distinguish temperature effects from pressure effects through differential measurement while reducing the overall device thickness by eliminating the need for multiple stacked layers.
Solution Approach 2:
The force sensors on the same layer serve multiple functions: detecting both temperature changes and pressure applied to the cover window. By designing the sensor system to handle both measurement types simultaneously on a single layer, the patent achieves multi-functionality without increasing device thickness.
2Measurement precision
If force sensors are disposed on different layers, then mounting space is secured for the sensors, but manufacturing costs increase
Solution Approach 1:
The patent combines multiple force sensors onto the same layer, which simplifies the manufacturing process by reducing the number of assembly steps required for stacking multiple layers. This merging approach lowers manufacturing costs while still providing the differential measurement capability needed for accurate pressure detection.
Solution Approach 2:
The patent changes the spatial arrangement parameter of the force sensors from a multi-layer configuration to a same-layer configuration. This parameter change simplifies manufacturing processes and reduces costs while maintaining the functional capability to distinguish temperature from pressure effects through differential measurement.
3Length of moving object
If force sensors are disposed on the same layer, then device thickness is reduced and manufacturing costs decrease, but the difference in resistance change due to pressure versus temperature is not large, making accurate pressure detection difficult
Solution Approach 1:
The patent applies different adhesive members with different rigidity characteristics at different locations under the force sensors. By controlling the local mechanical properties (rigidity) of the adhesive layers, the system enhances the differential response between temperature and pressure effects, allowing accurate pressure detection even with sensors on the same layer.
Solution Approach 2:
The adhesive members serve as intermediaries between the force sensors and the underlying structure. By carefully selecting adhesive members with appropriate rigidity, the system mediates the mechanical coupling to enhance the differential response to temperature and pressure, enabling accurate pressure detection through the ratio of resistance changes from multiple sensors.
4Manufacturing precision
If adhesive members with high rigidity are used under force sensors, then sensor deformation is minimized, but the sensors may be overly constrained affecting sensitivity
Solution Approach 1:
The patent changes the rigidity parameter of the adhesive members to an intermediate value that balances two competing requirements: providing enough constraint to maintain accurate sensor positioning while allowing sufficient movement to preserve sensor sensitivity. This optimized rigidity parameter achieves both positioning accuracy and sensing reliability.
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 solution allows for accurate detection of pressure while minimizing the impact of temperature changes, reducing the overall thickness and manufacturing costs of the electronic device.
Implementation Method 1
The force sensor may detect the magnitude of an input pressure based on a change in resistance generated when a metal is bent by the pressure applied to the display
Implementation Method 2
a first adhesive member provided on at least one area under the second sensor, wherein the second sensor is less deformed than the first sensor by the pressure applied to the cover window provided by the first adhesive member
Data Source
AI summary
An electronic device includes a cover window defining a front surface of the electronic device; a first sensor provided under the cover window and configured to detect a pressure applied to the cover window; a second sensor provided on a same layer as the first sensor and configured to detect the pressure applied to the cover window; a first adhesive member provided on at least one area under the second sensor, wherein the second sensor is less deformed than the first sensor by the pressure applied to the cover window provided by the first adhesive member; and a processor configured to: acquire a first pressure change amount detected by the first sensor and a second pressure change amount detected by the second sensor; and detect the pressure applied to the cover window based on the first pressure change amount and the second pressure change amount.