Earbud Charge-Contact Touch Sensing for Waterproof Input
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Solution Overview
Problem
Conventional ear-worn electronic devices rely on electromechanical switches or push buttons for user input, which are prone to electrostatic discharge, foreign material ingress, and reduce waterproofing, and have complex assembly and false actuation issues with inertial measurement unit switching and capacitive touch methods.
Innovation Solution
An ear-worn electronic device with a user-actuatable touch sensor using charge contacts and an auxiliary sensor to distinguish between skin contact and conductive materials, generating a touch signal for initiating device functions, and incorporating a threshold detector to differentiate impedance ranges for accurate input recognition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If electromechanical switches or push buttons are used for user input, then user input functionality is provided, but the device is prone to electrostatic discharge, foreign material ingress, and reduced waterproofing
Solution Approach 1:
The patent replaces electromechanical switches and push buttons with a capacitive touch sensor system. The touch sensor detects user input through changes in capacitance when a conductor (such as a finger) approaches or contacts the sensor surface, eliminating mechanical moving parts while maintaining user input functionality. This substitution resolves the contradiction by providing touch-based operation without the waterproofing vulnerabilities and electrostatic discharge risks associated with mechanical contacts.
Solution Approach 2:
The patent introduces an auxiliary sensor that detects the electrical properties (conductivity or impedance) of materials contacting the touch sensor. This intermediary sensor distinguishes between conductive materials (such as human skin) and non-conductive materials (such as hair or clothing), enabling the system to differentiate between intentional user input and environmental interference. This resolves the contradiction by adding a layer of intelligence that maintains reliable operation while protecting against false actuation from non-skin conductors.
2Ease of operation
If inertial measurement unit switching or capacitive touch methods are used, then user input is enabled, but false actuation and complex assembly issues occur
Solution Approach 1:
The patent combines the primary touch sensor with an auxiliary sensor into an integrated sensing system. The auxiliary sensor is positioned in close proximity to the touch sensor and works in conjunction with it to detect the electrical properties of contacting materials. This merging of sensing functions reduces overall system complexity by using a coordinated sensor pair rather than separate, complex false-detection algorithms, while still enabling reliable differentiation between skin contact and environmental interference.
Solution Approach 2:
The auxiliary sensor serves multiple functions: it detects the electrical properties of materials contacting the touch sensor, distinguishes between conductive and non-conductive materials, and provides data for the controller to determine whether a touch event represents intentional user input or environmental interference. This multi-functionality reduces the need for separate detection systems and simplifies the overall assembly while maintaining high reliability.
3Reliability
If a touch sensor is used for user input, then waterproofing is improved, but false actuation from conductive materials like hair or water may occur
Solution Approach 1:
The auxiliary sensor acts as an intermediary that provides additional information about the material contacting the touch sensor. By detecting the electrical properties (conductivity or impedance) of the contacting material, the auxiliary sensor enables the controller to distinguish between intentional user input (human skin) and environmental interference (hair, water, or other conductive materials). This intermediary sensing layer maintains waterproofing while improving input recognition accuracy through material differentiation.
Solution Approach 2:
The system uses feedback from the auxiliary sensor to adjust the interpretation of touch sensor signals. When the auxiliary sensor detects electrical properties consistent with non-skin conductive materials, the controller can filter or ignore corresponding touch events, preventing false actuation. This feedback mechanism maintains the simplicity and waterproofing of the capacitive touch system while eliminating false input from environmental conductors.
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 solution provides a reliable, waterproof, and low-power user input method that reduces false actuations and electrostatic discharge, enhancing the durability and functionality of ear-worn devices.
Implementation Method 1
The touch sensor comprises a threshold detector configured to distinguish between skin contact with the first and second charge contacts and contact between a conductive material more conductive than skin and the first and second charge contacts
Data Source
AI summary
An ear-worn electronic device comprises a housing configured to be worn in, at or about an ear of a wearer, electronic circuitry disposed in or supported by the housing, a controller disposed in the housing and coupled to the electronic circuitry, and a rechargeable power source and charging circuitry respectively disposed in the housing. The charging circuitry is coupled to the controller and comprises first and second charge contacts situated at a wall of the housing. A user-actuatable control is operatively coupled to the controller and comprises a touch sensor coupled to the first and second charge contacts. The touch sensor comprises a threshold detector configured to distinguish between skin contact with the first and second charge contacts and contact between a conductive material more conductive than skin and the first and second charge contacts.