Simultaneous Inductive-Capacitive Sensing for Durable Virtual Buttons

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Solution Overview

Problem

Existing mobile devices face challenges in detecting user interactions with human-machine interfaces due to the susceptibility of mechanical buttons to aging and wear, requiring sensitive sensors that consume low power and occupy minimal space.

Innovation Solution

A system utilizing a resistive-inductive-capacitive sensor with a measurement circuit to detect changes in capacitance and inductance, combined with electromagnetic shielding to enhance sensitivity to both capacitive and inductive changes, allowing for the detection of physical interactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If mechanical buttons are used in mobile devices, then user interaction reliability is improved, but device durability deteriorates due to aging and wear

Engineering Contradiction:

Improveuser interaction reliabilityVSAvoiddevice durability

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent replaces mechanical buttons with a virtual button system that uses capacitive and inductive sensing to detect user interactions. The sensor system measures changes in capacitance and inductance caused by finger proximity and contact, eliminating mechanical moving parts while maintaining button functionality. This substitution resolves the contradiction by providing reliable user interaction detection without the wear and aging problems of mechanical components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Duration of action of stationary object

If virtual buttons are used to replace mechanical buttons, then device durability is improved, but user experience deteriorates without mechanical feedback

Engineering Contradiction:

Improvedevice durabilityVSAvoiduser experience

Core Design Contradiction:

Duration of action of stationary objectVSEase of operation

Solution Approach 1:

The patent incorporates a linear resonant actuator that generates vibrations in response to detected user interactions with the virtual button. When the sensor detects a touch or press gesture, the actuator produces haptic feedback that mimics the tactile sensation of pressing a mechanical button. This vibration mechanism resolves the contradiction by providing mechanical-like feedback through a non-mechanical system, maintaining user experience while preserving device durability.

Inventive Principle:

Principle #18Mechanical vibration

Solution Approach 2:

The system uses feedback from the sensor detection to trigger haptic responses through the linear resonant actuator. The sensor continuously monitors capacitance and inductance changes, and when specific interaction patterns are detected, the system provides tactile feedback to confirm the interaction to the user. This feedback loop resolves the contradiction by creating a responsive interaction experience without mechanical components.

Inventive Principle:

Principle #23Feedback

3Difficulty of detecting and measuring

If traditional force or pressure sensors are used to detect user interaction, then interaction detection capability is improved, but power consumption and device size increase

Engineering Contradiction:

Improveinteraction detection capabilityVSAvoidpower consumption

Core Design Contradiction:

Difficulty of detecting and measuringVSUse of energy by moving object

Solution Approach 1:

The patent uses a multi-functional sensor system that simultaneously measures both capacitance and inductance changes using a single sensor element. This sensor can detect various types of user interactions including proximity, light touch, and firm press gestures by analyzing different aspects of the electrical field changes. The linear resonant actuator also serves dual purposes as both a haptic feedback device and a reference for vibration-based sensing. This multi-functionality resolves the contradiction by providing comprehensive interaction detection capability while minimizing power consumption and device size compared to traditional dedicated force or pressure sensors.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 system provides accurate detection of user interactions with virtual buttons, mimicking mechanical button feedback while optimizing power consumption and size, enhancing the durability and user experience.

Implementation Method 1

determine a change in capacitance and a change in inductance associated with the sensor

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

determine a change in capacitance and a change in inductance associated with the sensor

Methodology Applied

Scientific EffectInductance: Electromagnetic Induction

Implementation Method 3

an electromagnetic shield for a sensor may include shielding material configured to shield passage of electromagnetic energy and at least one void formed in the shielding material

Methodology Applied

Scientific EffectElectromagnetic shielding: Faraday Cage

Data Source

PatentUS20250231649A1Simultaneous inductive- and capacitive-based proximity, touch, and force sensing

Publication Date: 2025.07.17 CIRRUS LOGIC INC

AI summary

A system may include a sensor and a measurement circuit communicatively coupled to the sensor and configured to measure phase information associated with the sensor, based on the phase information, determine a change in capacitance and a change in inductance associated with the sensor, and detect physical interaction by a user with a mechanical member associated with the sensor based on the change in capacitance and the change in inductance.