Inductive Keyboard Key Sensing With Ferrite Sealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing keyboards are susceptible to damage or malfunction when exposed to fluids, and they lack effective non-contact mechanisms for measuring key depression distance and speed.
Innovation Solution
A key structure using a moving member with a magnet, coupled with an inductive sensor and a ferrite cover, measures the distance and speed of key depression through changes in inductance, and is designed to be sealed against fluid exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Hall effect sensors are used under every key to measure magnetic field strength, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
Multiple inductor sensors are merged into a single integrated circuit board, allowing one IC to measure multiple inductors positioned under different keys. This reduces the number of separate sensor components needed while maintaining measurement capability across all keys.
Solution Approach 2:
A single IC is designed to perform multiple measurement functions by reading impedance changes across multiple inductors simultaneously. This multi-functional approach allows one component to replace what would traditionally require multiple separate sensors.
2Ease of manufacture
If traditional ohmic contact switches are used, then manufacturing simplicity is maintained, but reliability deteriorates due to wear and tear
Solution Approach 1:
The traditional mechanical ohmic contact switch system is replaced with a magnetic field-based inductive sensing system. This substitution eliminates physical contact and mechanical wear while maintaining the switching functionality, thereby improving reliability without significantly complicating manufacturing.
3Ease of operation
If the keyboard is designed with exposed moving parts for key actuation, then ease of operation is improved, but susceptibility to fluid damage increases
Solution Approach 1:
The exposed mechanical moving parts are replaced with magnetic field sensing that can be performed through non-contact or sealed contact methods. This allows the keyboard to maintain operational responsiveness while protecting internal components from fluid exposure.
Solution Approach 2:
A ferrite layer is introduced as a protective barrier that can be sealed to protect the PCB and electronic components from fluid damage. This layer allows magnetic field penetration for sensing while providing physical protection against liquids.
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 reliable, non-contact switch system that is less prone to wear and tear and fluid damage, enabling accurate measurement of key depression distance and speed while maintaining keyboard functionality.
Implementation Method 1
use an inductive sensor and a ferrite cover that is adjacent to the said inductor. The inductive sensor is linked to an inductor that is positioned directly below the key
Implementation Method 2
The inductor, that may be formed on a printed circuit board (pcb), is covered with a ferrite member that actually increases the inductance of the inductor
Data Source
AI summary
The keys are fitted with small magnets and the movement of each key is detected and measured with inductive sensors that are adjacent to a ferrite member. The properties of the ferrite member change due to the proximity of the magnet, and these changes influence the inductive measurements. The ferrite member can be used to seal the electronics in a keyboard making it less prone to malfunction when coffee or other fluids are spilled onto it.