Key Assembly Plinth and Recessed Key Mat Design
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Solution Overview
Problem
Film-style key assemblies face issues such as keycaps being inadvertently peeled away and poor tactile feel due to the resilient material conforming to the sides of the silicone key mat, leading to increased actuation force and unwanted lateral interactions between adjacent keys.
Innovation Solution
A key assembly design featuring a keycap with a plinth extending from its underside, a recessed area in the key mat to receive the plinth, and an elastic layer with openings between the keycap and contact-responsive switch, which reduces perpendicular rigidity and improves tactile feel while preventing peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the resilient material conformally tracks the sides of the raised area of the silicone key mat, then the key assembly provides adequate structural support, but the actuation force increases and tactile feel deteriorates
Solution Approach 1:
The resilient material is segmented by introducing lateral release features (breaks or gaps) that divide the continuous material into separate sections. This segmentation allows the material to flex independently in different regions, reducing lateral force transfer while maintaining vertical support, thereby improving tactile feel without sacrificing structural integrity
Solution Approach 2:
The resilient material is designed with different properties in different regions: it maintains full continuity and support where needed, but incorporates lateral release features in specific areas to reduce rigidity. This local differentiation allows the material to provide structural support where required while enabling better tactile feedback in key actuation areas
2Stability of the object's composition
If the resilient material conformally tracks the sides of the raised area, then the keycap is securely positioned, but lateral force transfer increases causing unwanted interaction between adjacent keys
Solution Approach 1:
Lateral release features are introduced into the resilient material to segment it into independent zones. This segmentation prevents lateral forces from propagating between adjacent keys while maintaining vertical engagement, thereby eliminating crosstalk without compromising keycap positioning stability
Solution Approach 2:
The lateral release features act as intermediaries that allow controlled separation or movement in the resilient material. These features mediate between the keycap and the underlying structure, permitting lateral displacement to prevent force transfer while maintaining overall structural support
3Force
If the resilient material is used to bias the keycap away from the contact-responsive switch, then the key assembly provides necessary return force, but the keycap can be inadvertently peeled away when subjected to pulling force
Solution Approach 1:
The resilient material is segmented with lateral release features that create discrete engagement zones. This segmentation allows the material to maintain strong vertical engagement for return force while reducing lateral constraint, preventing peeling forces from propagating through the entire structure and improving keycap attachment reliability
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 enhances durability and tactile feedback while reducing the likelihood of keycap peeling and lateral crosstalk, resulting in a more reliable and user-friendly key assembly.
Implementation Method 1
an elastic layer... has at least one opening disposed therethrough... The elastic layer serves to aid in biasing the keycap away from the contact-responsive switch
Data Source
AI summary
A key assembly comprises a contact-responsive switch and a keycap having a plinth extending from an underside surface thereof. A key mat disposed between the keycap and the contact-responsive switch has a recessed area formed therein. This recessed area is sized and configured to receive the keycap's plinth. If desired, an adhesive can physically adhere the keycap to the key mat. By one approach, the key assembly also comprises a substantially-planar elastic layer disposed between the keycap and the contact-responsive switch. If desired, this elastic layer and the aforementioned key mat are integrally coupled to one another. By one approach this elastic layer has at least one opening disposed therethrough. This opening (or these openings) can be disposed at least in part in common with the aforementioned recessed area of the key mat.