Resistive Force Touch Sensing for Low Minimum Pressure
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Solution Overview
Problem
Existing force touch sensing technologies in small-sized electronic devices, such as smart watches, have high minimum sensing pressure due to a relatively small change in capacitance, limiting them to single touch detection and reducing sensitivity.
Innovation Solution
The implementation of a resistive type force touch sensing method using a force sensor member that changes shape to electrically connect parallel first and second electrodes, allowing for a low minimum sensing pressure and improved sensitivity through variations in resistance based on touch pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a capacitive type force sensing panel is used in a small-sized electronic device, then the device structure is simplified, but the minimum sensing pressure becomes high due to relatively small capacitance change
Solution Approach 1:
The patent replaces the capacitive sensing mechanism with a resistive sensing mechanism. The force sensing panel uses a force sensor member that changes resistance value when deformed by touch force, rather than measuring capacitance change. This substitution enables lower minimum sensing pressure while maintaining simplified device structure.
Solution Approach 2:
The patent changes the sensing parameter from capacitance to resistance. By using a force sensor member whose resistance value varies with deformation, the system achieves improved sensitivity and lower minimum sensing pressure compared to capacitive sensing in small-sized devices.
2Area of stationary object
If a singular whole electrode structure with small area is used, then the device size is reduced, but the minimum sensing pressure increases due to limited capacitance change
Solution Approach 1:
The patent replaces the electrode-based capacitive sensing structure with a resistive sensing structure using a force sensor member. This allows effective force sensing in small areas without the limitations of capacitance change, achieving both small device size and low minimum sensing pressure.
3Ease of manufacture
If a capacitive force sensing panel is used, then the manufacturing method is simplified, but only single touch force detection is enabled with reduced sensitivity
Solution Approach 1:
The patent changes the sensing parameter from capacitance to resistance, enabling multiple touch force detection levels. The force sensor member's resistance value varies continuously with deformation degree, allowing differentiation between light and heavy touch forces, thereby improving versatility while maintaining ease of manufacture.
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 enables a low minimum sensing pressure and enhanced sensitivity for force touch detection, allowing for multiple touch force sensing and improved user interaction in small-sized electronic devices.
Implementation Method 1
a force sensing panel 140 which senses a touch force in accordance with a user's touch pressure by a variation of resistance in a force sensor member 143
Implementation Method 2
whose shape is changed according to a touch pressure applied to a cover window so as to electrically connect first and second electrodes
Data Source
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Figure 5
AI summary
An electronic device is capable of having a minimum sensing pressure with a low value through a resistive type force touch sensing method, wherein the electronic device may include a force sensing panel having a force sensor member whose shape is changed according to a touch pressure applied to a cover window so as to electrically connect first and second electrodes prepared on the same plane and provided in parallel.