Planar Coil Linear Actuator for Broad Frequency Response
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Solution Overview
Problem
Existing vibro-tactile actuators have a narrow frequency response range, making them inadequate for applications requiring the transmission of a broader spectrum, such as voice communication, and are often bulky, heavy, and expensive.
Innovation Solution
A planar coil linear actuator utilizing a stack of independently-controlled flat coils with a common core and a mobile magnet, allowing for selective energization of coils to control frequency and amplitude, and integrated electronics on a multi-layer printed circuit board for a compact and wide frequency response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single coil with mobile rare-earth magnet is used in prior art vibro-tactile actuators, then the device achieves resonant frequency operation (200-300 Hz), but the frequency response range becomes narrow
Solution Approach 1:
The single coil is divided into multiple planar coils arranged in a stack configuration. Each coil can be independently controlled to drive the mobile magnet at different frequencies and amplitudes, enabling broad frequency response while maintaining reliable resonant operation when needed
Solution Approach 2:
The system transitions from fixed resonant frequency operation to dynamically adjustable frequency control. By selectively energizing different coils in the stack, the actuator can operate at any frequency within the broad response range, adapting to different application requirements
2Force
If traditional actuator design is used, then the device achieves adequate vibration output, but the device becomes bulky, heavy, and expensive
Solution Approach 1:
Traditional mechanical actuator components are replaced with planar coils fabricated as conductive traces on multi-layer printed circuit boards. This substitution maintains adequate vibration output while dramatically reducing weight and device complexity
Solution Approach 2:
The coil structure transitions from traditional three-dimensional windings to two-dimensional planar traces. This parameter change in coil geometry maintains electromagnetic performance while reducing material usage and device weight
3Force
If traditional actuator design is used, then the device achieves adequate vibration output, but the device becomes bulky and complex
Solution Approach 1:
Multiple coils that would traditionally be separate components are merged into a single integrated structure fabricated on multi-layer printed circuit boards. The conductive traces are formed as planar patterns on stacked board layers, creating a compact coil stack with reduced complexity
Solution Approach 2:
The coil structure transitions from three-dimensional windings to two-dimensional planar traces distributed across multiple board layers. This dimensional change enables compact integration while maintaining the necessary number of coils for broad frequency response
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
The solution provides a broad frequency response, enabling effective transmission of voice communication and other signals within a wider bandwidth, while being lightweight, thin, and inexpensive, suitable for wearable devices.
Implementation Method 1
A stack of individually driven planar coils are used. A common core passes through the center of the stack of coils. A mobile magnet resides in the core. The coils are selectively energized in order to drive the magnet as desired.
Implementation Method 2
The coils are selectively energized in order to drive the magnet as desired. It is possible to control both frequency and amplitude by controlling the motion of the magnet.
Data Source
AI summary
A planar coil linear actuator/transducer. A stack of individually driven planar coils are used. A common core passes through the center of the stack of coils. A mobile magnet resides in the core. The coils are selectively energized in order to drive the magnet as desired. It is possible to control both frequency and amplitude by controlling the motion of the magnet. In a preferred embodiment, each planar coil is created as a copper (or other conductive material) trace on a multi-layer printed circuit board.