Speaker Coil RF Antenna Integration for Space-Constrained Mobile Devices

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Solution Overview

Problem

Mobile computing devices face challenges in increasing battery capacity while maintaining compactness, as existing RF antennas occupy valuable space and increase the bill of materials cost.

Innovation Solution

Utilizing the coil of a dynamic speaker to transmit and receive RF signals above 100 kHz, eliminating the need for a separate RF antenna by integrating RF circuitry with the speaker amplifier, which includes low-pass and high-pass filters to prevent electromagnetic interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If separate RF antennas are used in mobile computing devices, then RF communication functions are enabled, but device space is consumed and battery capacity is reduced

Engineering Contradiction:

ImproveRF communication functionVSAvoiddevice space

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The speaker coil is designed to perform dual functions: audio output and RF antenna. The same coil structure that generates sound waves is also used to transmit and receive RF signals for NFC and other wireless communications, eliminating the need for separate RF antenna components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the RF antenna function with the existing speaker assembly. The speaker coil and RF antenna are merged into a single component, with the coil serving both audio and wireless communication purposes, thereby reducing overall device volume.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If separate RF antennas are used in mobile computing devices, then RF communication functions are enabled, but bill of materials cost increases

Engineering Contradiction:

ImproveRF communication functionVSAvoidbill of materials cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the RF antenna function with the existing speaker assembly. The speaker coil and RF antenna are merged into a single component, reducing component count and bill of materials cost.

Inventive Principle:

Principle #5Merging (Combining)

3Device complexity

If speaker coil is used for both audio and RF signals, then component count is reduced, but electromagnetic interference between audio and RF circuits may occur

Engineering Contradiction:

Improvenumber of componentsVSAvoidelectromagnetic interference

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

Filter circuits are introduced as intermediary components between the speaker coil and the audio/RF circuits. These filters act as mediators that allow the coil to serve dual purposes while preventing harmful electromagnetic interference between the audio amplifier and RF receiver/transmitter.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The harmful RF signals are extracted and blocked from the audio circuit path using filtering. The filter circuits separate the audio and RF signal paths, preventing RF interference from reaching the audio amplifier while allowing the coil to function for both purposes.

Inventive Principle:

Principle #2Taking out (Extraction)

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 approach reduces the number of antennas, freeing up space for battery expansion, lowering costs, and minimizing cross-coupling issues due to non-overlapping frequency bands, potentially increasing battery capacity by 5-10% and reducing BOM costs by no more than ten cents.

Implementation Method 1

a dynamic speaker comprising a speaker coil; a speaker amplifier to cause the dynamic speaker to produce sound

Methodology Applied

Scientific EffectElectromagnetic interaction: Lorentz Force

Implementation Method 2

radio frequency (RF) circuitry to cause the speaker coil to transmit a radio frequency signal having a frequency greater than about 100 kHz

Methodology Applied

Scientific EffectElectromagnetic radiation: Electromagnetic Induction

Data Source

PatentEP4432702A1Dynamic speaker coils as radio frequency antennas in mobile computing devices

Publication Date: 2024.09.18 INTEL CORP

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AI summary

The speaker coil in a dynamic speaker in a mobile computing device can be used to generate radio frequency (RF) signals having a frequency of about 100 kHz or greater. A speaker amplifier drives the dynamic speaker to produce sound and RF circuitry drives the speaker amplifier to generate the RF signals having a frequency of about 100 kHz or greater. The speaker coil can comprise a tap at an appropriate point between the ends of the coil to cause the coil to operate at resonance over a desired RF frequency band. A low-pass filter can be positioned at the speaker amplifier output to protect the speaker amplifier from RF energy generated by the RF circuitry and a high-pass filter can be positioned at the output of the RF circuitry to protect the RF circuitry from audio energy generated by the speaker amplifier.