Capacitive Force-Sensing Earphone Input Without Tapping Noise
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Solution Overview
Problem
Conventional earphones with mechanical input devices are difficult to operate when worn, as users cannot see the input 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 a non-binary amount of force applied to a housing input surface using a change in capacitance between first and second force electrodes, allowing activation without external mechanical input devices and reducing tapping-induced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If mechanical input devices (buttons, dials) are incorporated into earphones, then input functionality is improved, but ease of operation deteriorates because users cannot see the input devices when worn
Solution Approach 1:
The patent replaces mechanical input devices (buttons, dials, switches) with a capacitive sensing system that detects touch and force applied to the earphone housing. The controller monitors changes in capacitance between electrodes to determine user input, eliminating the need for visible mechanical components while maintaining input functionality.
2Ease of operation
If tapping is used to activate input devices, then ease of operation is improved, but object-generated harmful factors worsen due to sound disruption and microphone interference
Solution Approach 1:
The patent substitutes mechanical tapping detection with capacitive force sensing. The system detects the magnitude and duration of force applied to the housing through capacitance changes, allowing users to activate functions without physical tapping that creates sound disruption or microphone interference.
Solution Approach 2:
The patent introduces capacitive electrodes and a controller as intermediaries between user input and device activation. Instead of direct mechanical contact, the system uses electrical field detection to sense user intent, filtering out unwanted mechanical noise while preserving input functionality.
3Device complexity
If force electrodes are positioned close together to reduce housing thickness, then device complexity is reduced, but measurement precision deteriorates due to difficulty in determining non-binary force amounts
Solution Approach 1:
The patent changes the measurement parameter from binary (touch/no touch) to continuous capacitance values. By monitoring the magnitude of capacitance change and its duration, the system can determine different levels of force applied, enabling non-binary input recognition even with closely spaced electrodes.
Solution Approach 2:
The system uses feedback from the capacitance sensor to distinguish between different input types. By analyzing the magnitude and temporal characteristics of capacitance changes, the controller can differentiate between light touches, firm presses, and sustained forces, maintaining measurement precision despite reduced electrode spacing.
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 enables earphones to be activated by force without tapping, improving power usage and reducing noise disruption, thus enhancing user experience and battery life while preventing false inputs from head or face contact.
Implementation Method 1
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
Implementation Method 2
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
Implementation Method 3
a deformable material positioned between the flexible circuit and the conductive object operable to deform when a force is applied to the input surface
Data Source
AI summary
An earphone includes a speaker housing; a speaker positioned in the speaker housing; a stem extending from the speaker housing, the stem defining an input surface; a conductive object disposed within the stem; a flexible circuit positioned between the stem and the conductive object; a member positioned between the flexible circuit and the conductive object operable to allow the flexible circuit to move with respect to the stem; a force sensor electrode disposed within the flexible circuit; and a controller operable to determine an input to the earphone using a change in capacitance detected using the force sensor electrode, the change in capacitance corresponding to a non-binary amount of a force applied to the input surface. In some examples, the earphone further includes a touch sensor electrode disposed within the flexible circuit.