Capacitive Force-Sensing Earphone Input to Prevent False Taps

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Solution Overview

Problem

Conventional earphones with mechanical input devices are difficult to operate when worn, as users cannot see the devices and tapping to activate them can disrupt audio output and conduct sound, leading to unpleasant experiences and potential microphone interference.

Innovation Solution

The implementation of force-activated earphones that determine non-binary amounts of force applied to a housing using a change in capacitance between first and second force electrodes, with a spring member biasing the first force electrode towards the housing, allowing it to move towards the second electrode when force is applied, enabling activation without external mechanical inputs or tapping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If mechanical input devices (buttons, dials, switches) are incorporated into earphones, then the earphones can be controlled locally without external devices, but the devices become difficult to operate when worn and may conduct sound disrupting audio output

Engineering Contradiction:

Improvelocal control capabilityVSAvoidsound conduction and operational difficulty

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent replaces mechanical input devices (buttons, dials, switches) with a capacitive sensing system that detects force applied to the housing. The controller determines non-binary amounts of force using capacitance changes between force electrodes, eliminating the need for physical mechanical components that conduct sound and are difficult to operate when worn.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If tapping is used to activate earphones, then activation can be achieved without external mechanical devices, but tapping disrupts audio output and causes false inputs

Engineering Contradiction:

Improveactivation capabilityVSAvoidaudio disruption and false inputs

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The patent replaces tapping (mechanical impact) with force sensing through capacitance measurement. The system detects non-binary amounts of force applied to the housing using capacitance changes between electrodes, allowing intentional activation without the audio disruption and false inputs caused by tapping.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the detection parameter from binary touch/tap detection to continuous force measurement through capacitance changes. This allows the system to distinguish between intentional force application (activation) and accidental forces, preventing false inputs while maintaining activation capability.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If force electrodes are implemented using separate sections of flexible circuit, then the first force electrode can move toward the second electrode when force is applied, but the device complexity increases

Engineering Contradiction:

Improveforce detection capabilityVSAvoidflexible circuit structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the force detection function into the existing flexible circuit structure. The first and second force electrodes are implemented as separate sections of a single flexible circuit, utilizing the circuit's inherent flexibility to allow electrode movement when force is applied, thereby reducing overall device complexity while maintaining force detection capability.

Inventive Principle:

Principle #5Merging (Combining)

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 solution allows for efficient activation of earphones by force without the need for external mechanical devices, reduces power consumption, and prevents false inputs by distinguishing between intentional and accidental forces, thereby improving user experience and battery life.

Implementation Method 1

a spring member disposed within the housing biases the first force electrode towards the housing and allows it to move towards the second force electrode when the force is applied

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

A non-binary amount of a force applied to a force input surface defined by a housing is determinable using a change in a mutual capacitance between first and second force electrodes

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS11917355B2Force-activated earphone

Publication Date: 2024.02.27 APPLE INC

AI summary

An earphone includes a housing that defines a force input surface opposite a touch input surface. A spring member in the housing includes a first arm that biases a touch sensor toward the touch input surface. The spring member also includes a second arm that biases a first force electrode toward the housing and allows the first force electrode to move toward a second force electrode when a force is applied to the force input surface. A non-binary amount of the force is determinable using a change in a mutual capacitance between the first force electrode and the second force electrode. The mutual capacitance between the first force electrode and the second force electrode may be measured upon detecting a touch using the touch sensor.