Layered Capacitive Touch Keyboard With Tactile Key Feedback
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Solution Overview
Problem
Conventional capacitive keyboards face issues of high cost and lack of tactile feel, with contact keyboards being unreliable and susceptible to contamination, and contactless keyboards being expensive or lacking tactile feedback.
Innovation Solution
A capacitive touch keyboard design featuring a soft shielding layer, a soft intermediate layer, and a one-dimensional sensor layer, with a honeycomb pattern of hexagonal sensing cells connected to a capacitance sensing circuit, providing tactile feedback and gesture recognition through capacitance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional capacitive keyboard structure is used, then contactless operation is achieved, but tactile feel for depressing is lost
Solution Approach 1:
The keyboard is divided into separate functional layers: a soft shielding layer with keycap structure, a soft intermediate layer, and a sensor layer. This segmentation allows the upper layers to provide tactile feedback while the lower sensor layer detects capacitance changes, resolving the contradiction between tactile feel and contactless operation.
Solution Approach 2:
The soft intermediate layer acts as a mediator between the shielding layer and sensor layer. It transmits mechanical depression force from the shielding layer to the sensor layer while maintaining electrical isolation, enabling tactile feedback transmission without direct mechanical contact between moving parts.
2Ease of operation
If conventional capacitive keyboard structure is used, then contactless operation is achieved, but cost increases
Solution Approach 1:
The patent changes the sensing parameter from complex multi-plate capacitance measurement to simple single-plate capacitance detection. By using a one-dimensional array of sensing elements that measure capacitance to a single conductive plate, the manufacturing cost is reduced while maintaining contactless operation capability.
Solution Approach 2:
The patent extracts and eliminates the complex multi-plate structure from conventional capacitive keyboards. By using only a single conductive shielding plate instead of multiple interleaved plates, the structure is simplified, reducing manufacturing complexity and cost while preserving the contactless sensing function.
3Ease of operation
If contact keyboard is used, then tactile feel is provided, but reliability decreases due to contact points and contamination
Solution Approach 1:
The patent replaces the mechanical contact-based sensing system with a capacitive sensing system. Instead of detecting physical contact through electrical circuits that require direct contact between keycaps and switches, the system uses capacitance changes detected by the sensor layer, eliminating wear and contamination issues while maintaining tactile feedback through the soft shielding layer.
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 design offers a cost-effective, reliable, and tactile-sensitive capacitive touch keyboard with improved gesture recognition and reduced device size, providing clear tactile feedback and efficient key depression detection.
Implementation Method 1
When a user depresses a key 921 with his finger, the capacitance of the keyboard is changed and is detected by a sensing controller 922 as a key input
Data Source
AI summary
A capacitive touch keyboard includes a soft shielding layer, a soft intermediate layer, and a one dimensional sensor layer where the soft intermediate layer is interposed between the other two to form a capacitor structure. The soft shielding layer includes a ground plane, a dielectric material covering on the ground plane, and plural key areas at its outer surface. The one dimensional sensor layer includes plural sensing cells which correspond to the key areas, and respective cells are electrically connected to a capacitance sensing circuit. Therefore, features of more compact size, simplified structure design, and tactile feel are provided in a capacitive keyboard.