Capacitive Touch Sensor Frequency Segmentation
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Solution Overview
Problem
Current capacitive touch sensors face challenges in simultaneously measuring true capacitive touch and force applied to the sensor, often requiring separate mechanisms and experiencing interference or ambiguity in distinguishing between finger touch and force-based inputs.
Innovation Solution
A capacitive touch sensor design featuring interlaced arrays of conductors with a deformable dielectric material, capable of producing both fringing and parallel-plate capacitances, uses different frequencies to differentiate between true capacitive touch and force inputs by varying capacitance measurements, allowing for simultaneous detection of touch and force with enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single capacitive sensor mechanism is used to detect both touch and force, then device complexity is reduced, but measurement precision deteriorates due to inability to distinguish between finger touch and force-based inputs
Solution Approach 1:
The sensor system is segmented into two distinct measurement modes using different excitation frequencies: a first frequency range for detecting true capacitive touch (fringing field) and a second frequency range for detecting force (parallel-plate capacitance). This frequency-based segmentation allows a single physical sensor structure to perform two separate measurement functions simultaneously without interference, resolving the contradiction between device simplicity and measurement precision.
Solution Approach 2:
The system changes the operating parameter (excitation frequency) to differentiate between touch and force measurements. By sweeping through different frequency ranges and observing capacitance variations, the system can identify whether a contact is due to finger proximity (affecting fringing field at lower frequencies) or applied force (affecting parallel-plate capacitance at higher frequencies), thereby achieving precise measurement distinction without adding mechanical complexity.
2Measurement precision
If separate mechanisms are used for measuring true capacitive touch and force, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the touch detection and force detection mechanisms into a single capacitive sensor structure with interlaced conductor arrays. By combining both measurement capabilities in one physical system and using frequency-based differentiation, the invention achieves the measurement precision of separate mechanisms while avoiding their structural complexity.
Solution Approach 2:
The capacitive sensor is designed with multi-functionality to perform both true capacitive touch detection and force measurement using the same physical structure. The sensor responds to different types of inputs (proximity touch and applied force) by producing distinguishable electrical responses at different frequencies, eliminating the need for separate specialized mechanisms.
3Measurement precision
If frequency-based differentiation is used to distinguish touch from force, then measurement precision is improved, but use of energy increases due to frequency sweeping
Solution Approach 1:
Instead of continuously sweeping through the entire frequency range, the system applies partial action by selecting specific frequency points or narrow frequency bands for measurement. The controller can determine input type by comparing capacitance at selected frequencies rather than performing exhaustive frequency analysis, reducing computational and energy overhead while maintaining measurement precision.
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 design enables precise and simultaneous measurement of true capacitive touch and force applied, reducing ambiguity and improving the sensor's ability to distinguish between different types of inputs, enhancing user interaction and feedback.
Implementation Method 1
The first and second arrays are configured to produce an electric field with electric field lines that extend in a first direction towards a user of the sensor and in a second direction towards the ground plane
Implementation Method 2
capacitive touch sensor design featuring interlaced arrays of conductors with a deformable dielectric material, capable of producing both fringing and parallel-plate capacitances
Data Source
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AI summary
Methods, systems, and apparatus relate to touch sensors that are configured to measure a true capacitive touch and a force applied to the sensor from a user. Some implementations involve the measurement of force and true capacitive touch simultaneously in a touch capacitive sensor.