Layered Capacitive Keyboard Structure With Tactile Feedback
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Solution Overview
Problem
Conventional capacitive keyboards are expensive and lack tactile feedback, while contact keyboards suffer from poor reliability and contamination issues.
Innovation Solution
A capacitive touch keyboard design featuring a shielding layer, an intermediate layer, and a one-dimensional sensor layer with a flexible printed circuit connection, providing tactile feedback and gesture operation capabilities through a simplified structure that reduces device size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional capacitive keyboard structure is used, then contactless operation is achieved, but tactile feedback is lacking and cost is high
Solution Approach 1:
The keyboard is segmented into three distinct functional layers: shielding layer, intermediate layer, and sensor layer. Each layer performs a specific function, allowing the system to achieve tactile feedback through the compressible intermediate layer while keeping the sensor layer simple and cost-effective.
Solution Approach 2:
A compressible intermediate layer is introduced as a mediator between the shielding layer and sensor layer. This intermediate layer provides the tactile feedback mechanism through its compression under finger pressure, while also maintaining the capacitive sensing function without requiring complex mechanical structures.
2Ease of operation
If conventional capacitive keyboard structure is used, then contactless operation is achieved, but device cost is high
Solution Approach 1:
Dividing the keyboard into three simple layered structures makes each component easier and cheaper to manufacture independently. The shielding layer, intermediate layer, and sensor layer can be produced separately and assembled, reducing overall manufacturing complexity and cost.
Solution Approach 2:
The invention changes the structural parameters from complex multi-component assemblies to simple layered structures with clear interfaces. This parameter simplification directly reduces manufacturing steps and material costs while maintaining the capacitive sensing functionality.
3Ease of operation
If conventional contact keyboard is used, then tactile feedback is provided, but reliability is poor due to contact points
Solution Approach 1:
The invention replaces the mechanical contact-based switching system with a capacitive sensing system. Instead of relying on physical contact points that wear and fail, the system uses electrical field detection through the compressible intermediate layer, eliminating contact wear while maintaining tactile feedback.
Solution Approach 2:
The compressible intermediate layer serves as a mediator that transmits mechanical pressure from finger contact to the sensor layer without requiring direct mechanical contact between moving parts. This eliminates contact wear and improves reliability while preserving tactile feedback.
4Device complexity
If simplified one-dimensional sensor layer is used, then device size and cost are reduced, but sensing capability must be maintained
Solution Approach 1:
The sensor layer is designed with local sensing capabilities where each region corresponds to specific key areas. The one-dimensional sensor cells are strategically positioned to detect pressure changes in their respective local zones, maintaining key detection accuracy while using a simplified overall structure.
Solution Approach 2:
The system uses electrical field changes detected by the simplified sensor layer to infer mechanical pressure distribution. This substitution of direct mechanical measurement with electrical field sensing allows accurate key detection with fewer and simpler sensor elements.
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 enhances user experience with clear tactile feedback and gesture recognition, reducing device size and cost while avoiding the drawbacks of conventional contact and contactless keyboards.
Implementation Method 1
The intermediate layer is interposed between the ground plane of the shielding layer and the one-dimensional sensor layer, thereby forming a capacitor structure
Implementation Method 2
a clearance between the ground plane of the shielding layer and the sensing cells of the one-dimensional sensor layer changeable in response to a pressing operation... so that a change on the capacitance of the keyboard is generated
Data Source
AI summary
A capacitive touch keyboard includes a shielding layer, a 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 shielding layer includes a ground plane, and plural first key areas at its outer surface. The one-dimensional sensor layer includes plural sensing cells and plural second key areas where the first key areas correspond to the second key areas, and respective cells are electrically connected to a sensing circuit. Therefore, features of more compact size, simplified structure design, and tactile feel are provided in a capacitive keyboard.