ANR Headphone Tap Detection Using Amplifier Current Sensing
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Solution Overview
Problem
Conventional acoustic noise reduction (ANR) headphones lack the ability to distinguish between pressure changes caused by acoustic noise and user-initiated taps, leading to unreliable control of audio functions and mode changes.
Innovation Solution
An ANR audio system with a current sensor and signal conditioner module that differentiates between the electrical current consumption due to acoustic noise and user taps, using a tap event to control audio features and mode changes by interpreting the amplitude, waveform, and duration of the supply current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ANR headphones use pressure sensing to detect user input, then they can detect pressure changes, but they cannot distinguish between acoustic noise and user taps
Solution Approach 1:
The patent introduces a current sensor as an intermediary element that monitors the electrical current consumed by the acoustic driver amplifier. This current consumption serves as a mediator that indirectly reflects the mechanical state of the headphone (tapped vs. normal acoustic noise) without directly sensing pressure, thereby enabling reliable distinction between user taps and acoustic noise.
Solution Approach 2:
The patent replaces the conventional mechanical pressure sensing approach with an electrical current monitoring system. Instead of directly sensing mechanical pressure changes that cannot distinguish between noise and taps, the system measures electrical current characteristics (amplitude, waveform, duration) which provide reliable differentiation between user-initiated taps and acoustic noise events.
2Adaptability or versatility
If physical control buttons are added to ANR headphones, then control functionality is provided, but accessibility becomes difficult in certain environments
Solution Approach 1:
The patent replaces mechanical control buttons with a contactless tap detection mechanism. Users can control audio functions by simply tapping the headphone structure, which is detected through current consumption patterns. This eliminates the need for physical buttons that may be difficult to access in certain environments, providing a more versatile and ease-of-use control interface.
Solution Approach 2:
The tap detection mechanism serves multiple control functions (play/pause, volume control, mode switching) without requiring separate physical buttons for each function. The single tap interface provides universal access to all control features, improving ease of operation while maintaining full control functionality.
3Reliability
If current sensing is used to detect taps, then reliable tap detection is achieved, but additional components are required
Solution Approach 1:
The patent utilizes the existing electrical current consumption of the acoustic driver amplifier as the sensing mechanism. The system essentially 'senses' itself by monitoring its own operational characteristics (current draw) in response to different mechanical states (tapped vs. noise). This self-service approach achieves reliable tap detection without requiring entirely separate sensing hardware, thereby limiting the increase in device complexity.
Solution Approach 2:
The current sensor serves dual purposes: it monitors the operational status of the acoustic driver amplifier and simultaneously detects user taps through characteristic current patterns. This multi-functionality reduces the need for additional dedicated components, achieving reliable tap detection while minimizing the increase in system complexity.
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
Enables reliable detection and interpretation of user taps to control audio functions and mode changes within ANR headphones, eliminating the need for physical control buttons and improving usability, especially in environments where button access is difficult.
Implementation Method 1
A current sensor and signal conditioner module are provided which identify a user tap on the headphone
Implementation Method 2
an acoustic driver amplifier having a first driver amplifier input to receive a second supply current from the power supply through a second electrical path
Data Source
AI summary
An acoustic noise reduction (ANR) headphone described herein has current detection circuitry that detects current consumed by an acoustic driver amplifier as a result of pressure changes due to a tapping of the headphone. Tapping may be performed to change an audio feature or operating mode of the audio system for the headphone. The current detection circuitry senses a characteristic of the current consumed by the acoustic driver amplifier that can be used to determine an occurrence of a tap event. Examples of a characteristic include an amplitude, waveform or duration of the sensed current. Advantageously, the ANR headphones avoid the need for control buttons to initiate the desired changes to the audio feature or operating mode.