Deflection Web With Varying Thickness Flanges
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Solution Overview
Problem
Keypad assemblies in mobile communications devices face challenges in providing effective protection against water and contaminants while maintaining key depression guidance and tactile feedback, as existing deflection webs may not adequately counteract key depression forces and can cause stress concentrations and light leakage.
Innovation Solution
A keypad assembly design featuring a deflection web with radially outwardly extending flanges of varying thickness, anchored to a keypad base, which exerts a pre-load force and includes a light shielding layer to reduce stress and light leakage, using an elastomeric material for the flexible membrane and chamfers at actuator intersections to alleviate stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a deflection web is used to protect against water and contaminants, then protection against contaminants is improved, but stress concentrations occur causing light leakage
Solution Approach 1:
The flange thickness is varied locally along its length, being thicker at certain positions and thinner at others, to optimize the distribution of stress and prevent stress concentrations that cause light leakage while maintaining the protective function against contaminants
2Object-generated harmful factors
If the deflection web is made thinner to reduce stress, then stress concentrations are reduced, but protection against contaminants is weakened
Solution Approach 1:
The flange is designed with non-uniform thickness, being thicker at positions where structural support and contamination protection are needed, and thinner at positions where stress concentration would occur, thus simultaneously reducing stress while maintaining protection
Solution Approach 2:
The deflection web incorporates a light shielding layer in addition to the flexible membrane, creating a composite structure that provides both contamination protection and stress management while preventing light leakage
3Device complexity
If the deflection web structure is simplified, then device complexity is reduced, but tactile feedback and key depression guidance are insufficient
Solution Approach 1:
The deflection web uses a flexible membrane with radially outwardly extending flanges that provide tactile feedback and key depression guidance through their elastic deformation, achieving adequate guidance functionality with a relatively simple flexible structure rather than complex mechanical guides
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 the keypad's ability to withstand key depression forces, reduces stress concentrations, and minimizes light leakage, providing improved tactile feedback and protection against contaminants.
Implementation Method 1
a flexible membrane resiliently coupling each of the actuators together
Data Source
AI summary
A deflection web is provided for use in a keypad assembly. The deflection web comprises a plurality of actuators resiliently coupled together by a flexible membrane. Each actuator of the deflection web corresponds to a key of the keypad assembly, and for each actuator, the flexible membrane comprises a corresponding radially outwardly extending flange whose thickness varies in a direction from the corresponding actuator. In some instances, the thickness of the flange may increase as the flange extends a distance radially outward from its corresponding actuator. A method for creating the deflection web of the keypad assembly and a method for assembling the keypad assembly are also provided.