Dynamic Speaker Coil Antenna for Space-Saving Mobile RF
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Solution Overview
Problem
Mobile computing devices face challenges in increasing battery capacity due to space constraints, as existing designs often require multiple antennas for various functions, including RFID, which 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, thereby eliminating the need for a separate RF antenna, and incorporating low-pass and high-pass filters to protect the speaker amplifier and RF circuitry, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple antennas are used for cellular, Wi-Fi, Bluetooth, GPS, and NFC functions, then device functionality is improved, but device volume and bill of materials cost increase
Solution Approach 1:
The speaker coil is designed to perform dual functions: audio signal transmission and RF signal transmission for RFID/NFC operations. By making the speaker coil universal for both audio and RF purposes, the patent eliminates the need for separate RF antennas, thereby reducing device volume while maintaining full functionality across cellular, Wi-Fi, Bluetooth, GPS, and NFC operations.
Solution Approach 2:
The patent merges the RF antenna function with the speaker coil, combining two previously separate components into one. The speaker coil structure is utilized for both audio output and RF communication, consolidating components and reducing the overall device volume without compromising functional versatility.
2Adaptability or versatility
If multiple antennas are used for various wireless functions, then device functionality is improved, but bill of materials cost increases
Solution Approach 1:
The speaker coil serves multiple purposes including audio signal transmission and RF signal transmission for RFID and NFC functions. This multi-functionality reduces the quantity of separate components needed, thereby lowering the bill of materials cost while preserving full device functionality across multiple wireless communication standards.
Solution Approach 2:
By combining the RF antenna function with the existing speaker coil, the patent reduces the total number of components that need to be manufactured and assembled. This merging eliminates redundant components, directly reducing bill of materials cost while maintaining support for all required wireless functions.
3Device complexity
If speaker coil is used for RF signal transmission, then antenna count is reduced, but electromagnetic interference between audio and RF circuits may occur
Solution Approach 1:
The patent segments the frequency spectrum into distinct bands: audio signals occupy the lower frequency range (20 Hz to 20 kHz) while RF signals operate at higher frequencies (100 kHz and above, including RFID bands at 125 kHz, 13.56 MHz, and NFC bands). This frequency segmentation prevents overlap and interference between audio and RF operations, allowing the speaker coil to handle both functions simultaneously without harmful electromagnetic interactions.
Solution Approach 2:
The patent introduces filtering circuits as intermediary components between the speaker coil and both the audio amplifier and RF transceiver. These filters act as mediators that prevent RF signals from interfering with audio amplification and block audio signals from entering the RF circuitry, thereby eliminating electromagnetic interference while maintaining the dual-function capability of the speaker coil.
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, lowers costs, and minimizes electromagnetic interference, while ensuring non-overlapping frequency bands for audio and RF signals.
Implementation Method 1
the coil of a dynamic speaker to generate sound, and to transmit and receive radio frequency (RF) signals
Implementation Method 2
A speaker amplifier and an RF circuit conductively coupled to a dynamic speaker cause the speaker to produce sound
Data Source
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.