Capacitive Touch Sensor Force Detection via Resistance
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Solution Overview
Problem
Existing input devices for smaller electronic devices, such as smartphones, face limitations due to the impracticality of larger devices like keyboards or mice, necessitating the development of compact solutions that can detect both touch and force using the same components.
Innovation Solution
A capacitive touch sensor system with transversely positioned rows and columns of electrodes separated by a dielectric, where the controller detects touch via mutual capacitance changes and determines force by analyzing resistance changes, allowing for simultaneous touch and force detection using the same components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate touch sensors and force sensors are used, then detection accuracy is improved, but device complexity and size increase
Solution Approach 1:
The patent combines touch detection and force detection functions into a single sensor system. The same electrode grid and controller are used to detect both touch events (via mutual capacitance changes) and force events (via self-capacitance changes), eliminating the need for separate sensor systems while maintaining detection accuracy for both functions.
Solution Approach 2:
The sensor system is designed to perform multiple functions using the same components. The electrode grid and controller serve dual purposes: detecting touch through mutual capacitance and detecting force through self-capacitance changes, making the sensor system universal and multi-functional.
2Adaptability or versatility
If multiple separate sensors are used for touch and force detection, then detection capability is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges touch and force detection into a single sensor system with shared components (electrode grid, dielectric layer, controller). This consolidation reduces the total number of parts that need to be manufactured and assembled, thereby lowering manufacturing costs while maintaining versatile detection capability.
Solution Approach 2:
By designing a universal sensor system that can detect both touch and force using the same hardware components, the patent reduces manufacturing complexity and cost. The single sensor system performs multiple detection functions, eliminating the need to manufacture and integrate separate specialized sensors.
3Adaptability or versatility
If touch and force detection are performed simultaneously, then functionality is improved, but signal interference increases
Solution Approach 1:
The controller performs touch detection and force detection at different time intervals or cycles. By periodically alternating between measuring mutual capacitance (for touch) and self-capacitance (for force), the system achieves simultaneous functionality while preventing signal interference through temporal separation of measurement operations.
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
Enables more compact and cost-effective sensor and electronic device designs capable of accurately determining both touch and force, including multiple simultaneous touches and force amounts, while preventing interference between touch detection and force determination.
Implementation Method 1
The controller is operable to detect a touch of an object to the cover glass using a mutual capacitance between the set of row electrodes and the set of column electrodes
Implementation Method 2
The force exerted by the touch may deform the electrodes and alter their resistance. The touch sensor may determine the non-binary amount of the force based on changes in resistance
Data Source
AI summary
An electronic device includes a surface such as a cover glass, a first group of electrodes coupled to the surface and arranged in a first direction with respect to the surface, a second group of electrodes coupled to the surface and arranged in a second direction with respect to the surface, a dielectric separating the first and second groups of electrodes, and a controller electrically connected to the first and second groups of electrodes. The controller is operable to detect a touch of an object to the surface using a mutual capacitance between the first and second groups of electrodes and determine a non-binary amount of force exerted based on resistances of the first and second groups of electrodes.