Inductor Coil Layout for Far-Field Interference Cancellation
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Solution Overview
Problem
Existing sensors for detecting user interaction with human-machine interfaces in mobile devices face challenges in achieving acceptable levels of sensor sensitivity, power consumption, and size, while also being susceptible to external electromagnetic interference.
Innovation Solution
The proposed solution involves an inductive-based sensing apparatus with a unique configuration of inductor coils and mechanical members, where the inductor coils are arranged in a specific pattern to cancel out external electromagnetic interference and enhance sensitivity and power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an inductive-based sensor uses a single inductor coil to detect user interaction, then the sensor structure is simple, but the sensor is sensitive to external electromagnetic fields causing far field interference
Solution Approach 1:
The patent divides a single inductor coil into multiple inductor coils (first inductor coils and second inductor coils) arranged in a specific pattern. Each coil is electrically coupled and contributes to the overall sensing function while the segmented arrangement enables interference cancellation through differential measurement, resolving the contradiction between structural simplicity and interference resistance.
Solution Approach 2:
The patent employs an asymmetric arrangement of inductor coils where first inductor coils and second inductor coils are positioned at different locations relative to the mechanical member. This asymmetric configuration creates differential sensing paths that are equally affected by far field interference but differently by mechanical member displacement, enabling interference rejection while maintaining sensitivity to user interaction.
2Measurement precision
If traditional force or pressure sensors are used to detect user interaction, then sensor sensitivity can be achieved, but power consumption and device size increase
Solution Approach 1:
The patent replaces traditional mechanical force or pressure sensors with an inductive sensing system that uses electromagnetic fields to detect mechanical member displacement. This substitution eliminates the need for complex mechanical sensing elements, reducing power consumption and device size while maintaining measurement precision through the inductive coupling between inductor coils and the mechanical member.
3Reliability
If mechanical buttons are used in mobile devices, then user interaction detection is reliable, but the device becomes susceptible to aging and wear reducing useful life
Solution Approach 1:
The patent replaces mechanical buttons with a virtual button interface that uses inductive sensing to detect user interaction. The mechanical member in the inductive sensor experiences minimal wear as it only requires small displacements to change the inductive coupling, significantly extending the device's useful life while maintaining reliable user interaction detection through the electrical sensing mechanism.
4Object-affected harmful factors
If virtual buttons are used to replace mechanical buttons, then device waterproofing is improved, but user experience suffers without tactile feedback
Solution Approach 1:
The patent incorporates a linear resonant actuator that generates mechanical vibration in response to detected user interaction with the virtual button. This vibration provides tactile feedback that mimics the sensation of pressing a mechanical button, enhancing user experience while the inductive sensing mechanism maintains waterproofing by eliminating exposed mechanical contacts.
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 configuration effectively reduces interference from external electromagnetic fields, improves sensor sensitivity, and optimizes power consumption, resulting in a more reliable and efficient detection of user interactions with human-machine interfaces.
Implementation Method 1
When current flows through the inductor, the magnetic field induced by the current further induces an eddy current inside the metal plate
Implementation Method 2
When force is applied to the metal plate, changing the distance between the metal plate and the inductor, the coupling between the inductor and metal plate changes, thus modifying an effective impedance seen at the terminals of the inductor
Implementation Method 3
the plurality of first inductor coils and the plurality of second inductor coils are electrically coupled to one another and arranged with respect to one another such that within the plane, electrical current flowing through the inductor flows clockwise in the first inductor coils, within the plane, electrical current flowing through the inductor flows counterclockwise in the second inductor coils
Data Source
AI summary
A method may include forming an inductor comprising a plurality of inductor coils comprising a plurality of first inductor coils and a plurality of second inductor coils, each inductor coil comprising a spiraling wire of electrically-conductive material wherein the wire of electrically-conductive material is arranged substantially in a plane, wherein the plurality of first inductor coils and the plurality of second inductor coils are electrically coupled to one another and arranged with respect to one another such that within the plane, electrical current flowing through the inductor flows clockwise in the first inductor coils, within the plane, electrical current flowing through the inductor flows counterclockwise in the second inductor coils, each first inductor coil is adjacent to at least one second inductor coil, and each second inductor coil is adjacent to at least one first inductor coil.