Capacitive Keyswitch Layout for Tactile Input Without Ghosting
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Solution Overview
Problem
Conventional keyboards rely on non-tactile conductive-based switches that lack feedback, requiring complex and costly manufacturing processes for integrating touchpad and keyboard controllers, and suffer from key ghosting and jamming issues due to their matrix layout.
Innovation Solution
A capacitance-based keyswitch technology using a floating electrode paired with a fixed electrode to measure changes in capacitance, allowing for keypress detection without physical contact, and a single controller to manage both keyswitch matrix and touchpad signals, reducing the need for multiple controllers and addressing key ghosting through independent sensor matrices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional non-tactile conductive-based switches are used, then keypress detection is achieved, but tactile feedback is lost and manufacturing complexity increases
Solution Approach 1:
The patent replaces conventional mechanical conductive-based switches with a capacitive sensing system that uses electrical fields to detect keypresses. The floating electrode moves with the key, changing capacitance values that are detected by the controller, eliminating the need for complex multi-layer conductive structures while providing tactile feedback through the key's mechanical movement.
Solution Approach 2:
The capacitive keyswitch structure serves multiple functions: the floating electrode provides both the tactile feedback mechanism (through its physical movement with the key) and the sensing element (through capacitance changes). This unified structure eliminates the need for separate tactile and sensing components, simplifying manufacturing.
2Device complexity
If multiple controllers are used for keyboard and touchpad, then functional separation is achieved, but device complexity and cost increase
Solution Approach 1:
The patent integrates both keyboard and touchpad control functions into a single controller. The controller reads capacitance values from both the keyswitch matrix and touchpad sensors, determining whether inputs originate from keyboard keys or touchpad gestures. This consolidation reduces the number of controllers needed while maintaining reliable signal management through software-based function differentiation.
3Area of stationary object
If matrix layout is used for multiple keys, then space efficiency is achieved, but key ghosting and jamming issues occur
Solution Approach 1:
The patent replaces the conventional mechanical matrix switch layout with a capacitive sensing matrix. Each key position has a floating electrode that moves independently, creating unique capacitance change patterns when pressed. This capacitive matrix approach maintains space efficiency while eliminating key ghosting and jamming by using electrical field sensing instead of mechanical contact detection.
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
Enables a thin, low-profile keyboard with tactile feedback, efficient manufacturing, and effective gesture detection, while reducing key ghosting and jamming by using a single controller for both keyswitch matrix and touchpad, enhancing user input recognition and device usability.
Implementation Method 1
The floating electrode pairs with a fixed electrode and a capacitance may be generated between them. The apparatus has a controller configured to measure the capacitance as the electrodes move relative to each other as the key is depressed and released.
Data Source
AI summary
Described herein are techniques related to capacitance-based keyswitch technologies. According to one implementation, an apparatus includes a key with a floating electrode. The floating electrode pairs with a fixed electrode and a capacitance may be generated between them. The apparatus has a controller configured to measure the capacitance as the electrodes move relative to each other as the key is depressed and released. This Abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.