Pivoting Key Assembly for Thin Mobile Devices
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Solution Overview
Problem
Modern keypad and keyboard designs in handheld electronic devices face challenges in providing stable, illuminated, and tactilely feedback-rich keys within a thin profile, often resulting in wobbly and unstable keys due to the use of dome switches.
Innovation Solution
A key assembly featuring double keys with a deflection web and actuators, where each key pivots about two external contact portions to actuate separate switches, providing stability and tactile feedback, and incorporating a deflection web support with legs between actuators to enhance key stability and light transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If dome switches are used to provide a thinner device profile, then device thickness is reduced, but key stability and durability deteriorate resulting in wobbly and unstable keys
Solution Approach 1:
The key assembly is segmented into multiple functional components: a deflection web layer, individual key elements, and a support structure with legs. This segmentation allows each component to perform its specific function - the deflection web provides tactile feedback, the keys provide input, and the support legs provide stability - while working together to resolve the contradiction between thin profile and key stability.
Solution Approach 2:
The key assembly uses a composite structure combining a flexible deflection web material with rigid key elements and support structures. This composite approach allows the thin deflection web to provide tactile feedback while the rigid key elements and support legs maintain key stability and prevent wobbling, resolving the contradiction between thickness and stability.
2Length of stationary object
If dome switches are used to reduce device profile, then device thickness is reduced, but key durability worsens making keys more prone to damage
Solution Approach 1:
The deflection web acts as a cushioning element between the key elements and the dome switches. It absorbs and distributes mechanical stress and impacts before they reach the dome switches, providing beforehand cushioning that protects the switches from damage while maintaining the thin profile required by the design.
Solution Approach 2:
The deflection web is implemented as a flexible thin film structure that spans across the dome switches. This flexible film provides durability by distributing loads across multiple points and absorbing shocks, while maintaining the thin overall structure needed for a sleek device profile.
3Loss of information
If visual separation between keys is provided, then key distinguishability is improved, but device complexity increases
Solution Approach 1:
The key assembly merges multiple functions into unified components. The key elements serve both as tactile input surfaces and as visual indicators through illumination. The deflection web simultaneously provides structural support, tactile feedback, and spacing between keys. This merging reduces overall assembly complexity while maintaining key distinguishability.
Solution Approach 2:
Each component in the key assembly is designed with multi-functionality. The key elements provide both tactile input and visual display functions. The deflection web provides structural support, tactile feedback, and optical separation. This universality allows visual separation between keys to be achieved through the inherent structure and illumination capabilities of existing components rather than adding separate separation elements, thereby avoiding increased complexity.
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 results in more stable and less prone to damage double keys that offer pleasing tactile feedback and illumination, improving user experience while maintaining a thin device profile.
Implementation Method 1
A key assembly features double keys with a deflection web and actuators, where each key pivots about two external contact portions to actuate separate switches, providing stability and tactile feedback
Data Source
Figure 1
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AI summary
A key assembly for an electronic device comprises at least one key including a body having a first external contact portion and a second external contact portion. The first external contact portion is movable to thereby actuate a first switch of a pair of switches. The second external contact portion is movable to thereby actuate a second switch of the pair of switches. The body of the at least one key pivots about the first external contact portion when the second external contact portion moves to thereby actuate the second switch. The body of the at least one key also pivots about the second external contact portion when the first external contact portion moves to thereby actuate the first switch.