Transcapacitive Touch and Force Sensing in Input Devices
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Solution Overview
Problem
Current input devices, such as touchpads and touch screens, face challenges in simultaneously detecting the presence, position, and force of input objects using capacitive sensing, as they often require separate sensing modes and struggle to accurately measure changes in capacitance for both proximity and force sensing.
Innovation Solution
The implementation of a processing system in an input device that operates in both proximity and force sensing modes, utilizing a combination of touch electrodes and force electrodes to determine the position and force of input objects based on transcapacitive measurements, allowing for simultaneous detection of touch and applied force through changes in capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate sensing modes are used for proximity and force detection, then the device can detect input objects, but it cannot simultaneously determine both position and force accurately
Solution Approach 1:
The patent implements a unified capacitive sensing system that performs both proximity detection and force measurement through a single electrode structure and processing framework. The same touch electrodes serve dual purposes: detecting the presence/position of input objects in proximity mode and measuring applied force in force sensing mode, eliminating the need for separate sensing systems and enabling simultaneous accurate measurement of both parameters
Solution Approach 2:
The system dynamically switches between proximity sensing and force sensing modes based on operational requirements, with the processing system capable of adapting its measurement parameters and signal processing algorithms to optimize performance for the current sensing mode while maintaining accurate simultaneous detection capabilities
2Ease of operation
If traditional capacitive sensing is used, then the device can detect touch presence, but it struggles to accurately measure changes in capacitance for both proximity and force sensing
Solution Approach 1:
The patent replaces traditional mechanical force sensors with a capacitive sensing mechanism that measures force through changes in capacitance between electrodes. This substitution enables the system to detect both proximity and force using electrical field interactions rather than mechanical contact, significantly improving measurement precision for both parameters while maintaining ease of operation
Solution Approach 2:
The patent introduces an intermediary capacitive measurement mechanism that translates both proximity and force inputs into measurable capacitance changes. By using the electrical field as an intermediary between the physical input (touch/force) and the digital measurement system, the patent achieves accurate simultaneous measurement of both parameters through a unified capacitive sensing approach
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 accurate and simultaneous detection of input object position and force, enhancing the functionality of input devices by integrating transcapacitive proximity and force sensing capabilities, improving user interaction and feedback.
Implementation Method 1
determine a position of an input object, within a sensing region defined by the plurality of touch electrodes, based at least in part on a transcapacitive proximity measurement acquired from the touch receiver electrodes
Implementation Method 2
determine a force of the input object based at least in part on a transcapacitive force measurement. The transcapacitive force measurement is acquired from at least one of the touch transmitter electrodes or the touch receiver electrodes and is based on a change in capacitance between the plurality of force electrodes and the at least one of the touch transmitter electrodes or the touch receiver electrodes
Data Source
AI summary
An example input device for force and proximity sensing includes a plurality of touch electrodes comprising touch transmitter electrodes and touch receiver electrodes, a force electrode layer comprising a plurality of force electrodes, and a processing system. When operating in a proximity sensing mode, the processing system drives the touch transmitter electrodes with touch transmitter signals and determines a position of an input object, within a sensing region defined by the plurality of touch electrodes, based at least in part on a transcapacitive proximity measurement acquired from the touch receiver electrodes. When operating in a force sensing mode, the processing system drives the plurality of force electrodes with force transmitter signals and determines a force of the input object based at least in part on a transcapacitive force measurement based on a change in capacitance between the plurality of force electrodes and the plurality of touch electrodes.