Mobile Speaker Tactile Input via Acoustic Impedance Sensing

Solution Overview

Problem

Current mobile devices lack an effective method to detect tactile input for gaming and other applications using their built-in speakers, as existing technologies do not efficiently convert finger pressure into recognizable signals for user interaction.

Innovation Solution

The implementation of a tactile interface using stereo earbuds or the phone's body speaker, where phase shifts between voltage and current signals are detected due to changes in acoustic impedance caused by finger pressure, allowing for the recognition of tactile events and varying levels of pressure through phase shift analysis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If speakers are used for audio output only, then audio functionality is maintained, but tactile input capability is lost

Engineering Contradiction:

Improvespeaker functionalityVSAvoidtactile input detection

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The speaker is designed to serve dual purposes: traditional audio output and tactile input detection. By incorporating impedance sensing capability, the speaker can detect finger pressure and gestures while maintaining its audio function, thus achieving multi-functionality without requiring separate components for each purpose.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The speaker system performs self-diagnosis through impedance sensing. The same electrical signals used to drive the speaker for audio output are simultaneously monitored to detect tactile input. This self-service approach eliminates the need for separate sensors or additional hardware, allowing the speaker to serve both audio and input detection functions independently.

Inventive Principle:

Principle #25Self-service

2Measurement precision

If additional tactile sensors are added, then tactile input detection is improved, but device complexity increases

Engineering Contradiction:

Improvetactile input detection accuracyVSAvoidhardware components

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The existing speaker components are made multi-functional by adding impedance sensing capability. The speaker both produces audio and detects tactile input through the same physical component, eliminating the need for separate sensors and reducing overall device complexity while maintaining detection accuracy.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The speaker system performs self-diagnosis through impedance sensing. The same electrical signals used to drive the speaker for audio output are simultaneously monitored to detect tactile input. This self-service approach eliminates the need for separate sensors or additional hardware, allowing the speaker to serve both audio and input detection functions independently.

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If impedance sensing is implemented, then tactile input detection is enabled, but signal processing complexity increases

Engineering Contradiction:

Improveinput detection capabilityVSAvoidsignal processing

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The impedance sensing functionality is merged with the existing audio signal processing pathways. The same analog signal processing circuitry that handles audio output is utilized to monitor speaker impedance and detect tactile input, combining multiple functions within existing processing infrastructure rather than creating separate processing chains.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The speaker system performs self-diagnosis through impedance sensing. The same electrical signals used to drive the speaker for audio output are simultaneously monitored to detect tactile input. This self-service approach eliminates the need for separate sensors or additional hardware, allowing the speaker to serve both audio and input detection functions independently.

Inventive Principle:

Principle #25Self-service

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 the use of mobile device speakers as tactile input devices, allowing for precise detection of finger pressure and movement, enhancing gaming and other interactive experiences without the need for additional hardware, with phase shifts of up to 20 degrees accurately indicating finger presence and pressure levels.

Implementation Method 1

detects phase shifts in audio signals due to changes in acoustic impedance caused by finger pressure

Methodology Applied

Scientific EffectAcoustic impedance: Acoustics

Implementation Method 2

detects phase shifts in audio signals due to changes in acoustic impedance caused by finger pressure, allowing for the recognition of tactile events

Methodology Applied

Scientific EffectPhase shift detection:

Data Source

PatentUS8179235B2Tactile interface for mobile devices

Publication Date: 2012.05.15 TEXAS INSTRUMENTS INC

AI summary

A tactile input to a system having a speaker located in an enclosure with an audio port can be detected by generating a sound wave in response to a signal and sensing the phase relationship between the current phase and the voltage phase of the signal. While the audio port is open a baseline current and voltage phase difference is established. When the audio port is obstructed by a finger touch, the current and voltage phase difference is altered in response to the obstruction. While the altered phase difference is detected, a tactile event is indicated.