Planar Voice Coil Actuator on Multi-Layer Board
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Solution Overview
Problem
Modern consumer electronics, such as smartphones and portable computers, face challenges in providing sufficient acoustic output due to limited space, leading to reliability issues with micro-speakers and actuators caused by wire fatigue and breakage.
Innovation Solution
The use of traces on a multi-layer board (MLB) to create a planar voice coil immersed in a magnetic field, generated by surface-mounted magnets, allows for relative motion and sound radiation when current is applied, enhancing acoustic output while minimizing space and reducing wire-related reliability issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional micro-speakers with moving coils and wires are used, then acoustic output can be achieved, but wire fatigue and breakage occur leading to reliability issues
Solution Approach 1:
The patent extracts and eliminates the wire connections from the traditional moving coil motor structure. Instead of using separate wires to connect the voice coil to external circuitry, the voice coil is formed directly by conductive traces on the PCB, thereby removing the source of wire fatigue and breakage while maintaining the electrodynamic actuation function.
Solution Approach 2:
The patent merges the voice coil structure with the PCB by forming the voice coil directly from conductive traces on the board. This integration combines previously separate components (PCB and voice coil) into a unified structure, eliminating the need for wire connections and improving reliability.
2Productivity
If larger acoustic output devices are used, then acoustic performance improves, but device space requirements increase
Solution Approach 1:
The patent makes the PCB serve multiple functions: it provides structural support, electrical connectivity, and houses the voice coil through its conductive traces. This multi-functionality allows the same component to contribute to both mechanical support and acoustic generation, maximizing acoustic output within limited space.
Solution Approach 2:
The patent utilizes the two-dimensional plane of the PCB to create the voice coil structure through traces, rather than using a traditional three-dimensional wound coil. This planar configuration allows for efficient use of available space while maintaining the necessary electromagnetic interaction for acoustic output.
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 solution enables efficient sound radiation with improved reliability by utilizing the existing MLB and surface-mounted magnets, allowing for enhanced acoustic performance in compact electronic devices without the drawbacks of traditional micro-speakers.
Implementation Method 1
If current is applied to the coil, the Lorentz force actuates the MLB, which in turn, radiates sound
Implementation Method 2
a polarized magnet array having a magnetic field aligned to the planar voice coil to actuate the actuation region upon application of a voltage to the planar voice coil
Data Source
AI summary
An actuator assembly comprising: a multi-layer board comprising a first side and a second side defining an actuation region having a thickness that is reduced relative to a remainder of the multi-layer board; a planar voice coil formed by a trace on at least one of the first side or the second side defining the actuation region; and a polarized magnet array having a magnetic field aligned to the planar voice coil to actuate the actuation region upon application of a voltage to the planar voice coil.