Narrow Key Switch With Segmented Scissor Linkage
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Solution Overview
Problem
There is a challenge in designing keyboards for portable computing devices that are both aesthetically pleasing and provide tactile feedback, while also being smaller and lighter, without compromising user functionality.
Innovation Solution
A reduced footprint keyboard design featuring narrow keys with a two-part scissor mechanism and an elastomeric dome that activates electrical switch circuitry, allowing for a full-sized dome to provide tactile feedback despite a narrower key width, achieved through separate linkage structures and a link bar for mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the keyboard is made smaller and lighter for portable computing devices, then the footprint and weight are reduced, but the key width must be narrowed which compromises tactile feedback quality
Solution Approach 1:
The scissor mechanism is divided into two separate linkage structures positioned on opposite sides of the dome. This segmentation allows each linkage structure to independently support the key cap while maintaining adequate space for a full-sized elastomeric dome, thus preserving tactile feedback quality while achieving a narrower key width and reduced keyboard footprint
Solution Approach 2:
The two-part scissor mechanism utilizes vertical and lateral spatial arrangement to distribute structural support functions across different dimensions. By positioning linkage structures on opposite sides and using a link bar for rotational engagement, the design creates efficient space utilization that accommodates full-sized domes within narrow key constraints
2Ease of operation
If a full-sized elastomeric dome is used to provide adequate tactile feedback, then tactile response quality is maintained, but the key width must be increased which enlarges the keyboard footprint
Solution Approach 1:
The scissor mechanism is divided into two separate linkage structures positioned on opposite sides of the dome. This segmentation allows each linkage structure to independently support the key cap while maintaining adequate space for a full-sized elastomeric dome, thus preserving tactile feedback quality while achieving a narrower key width and reduced keyboard footprint
Solution Approach 2:
The linkage structures are positioned specifically on opposite sides of the dome, concentrating support functions where needed. This localized arrangement optimizes space utilization by placing structural elements only where required for support, rather than distributing them uniformly, thereby creating room for full-sized domes within narrow key constraints
3Area of stationary object
If narrow keys are used to reduce keyboard footprint, then the device size is reduced, but the mechanical stability and load distribution to the center dome area becomes insufficient
Solution Approach 1:
The scissor mechanism is divided into two separate linkage structures positioned on opposite sides of the dome. This segmentation allows each linkage structure to independently support the key cap while maintaining adequate space for a full-sized elastomeric dome, thus preserving tactile feedback quality while achieving a narrower key width and reduced keyboard footprint
Solution Approach 2:
A link bar is rotatably engaged with the key cap to transfer load from the side of the key to the center. This intermediary component acts as a mediator that redistributes lateral forces applied to the narrow key cap toward the central dome area, ensuring adequate load distribution and mechanical stability despite the reduced key width
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 design allows for a compact keyboard with positive tactile response and reduced footprint, maintaining user satisfaction in tactile feedback and functionality.
Implementation Method 1
an elastomeric dome that can activate electrical switch circuitry below the dome when the dome is deformed
Data Source
AI summary
A narrow key switch for a low travel keyboard and methods of fabrication are described. The low-travel keyboard having narrow keys is suitable for a thin-profile computing device, such as a laptop computer, netbook computer, desktop computer, etc. The keyboard includes a key cap positioned over an elastomeric dome and a two-part scissor mechanism having two separate linkage structures on opposite sides of the dome. A link bar is also provided to transfer a load from a side of a key to the center if the key cap is depressed in an off-center manner. Transferring the load to the center helps to deform the elastomeric dome so that it can activate the switch circuitry of the membrane on printed circuit board underneath the dome. Separating the linkage structures into two separate parts allows for the use of a full-sized elastomeric dome for a narrow key switch. The full-sized dome provides the desired tactile feedback to a user. Thus, the tactile feel of the key is not compromised even thought the key is narrower than a conventional key.