Key Sheet Sagging Prevention via Segmented Pin Holes
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Solution Overview
Problem
Conventional electronic devices with a key input section face issues where the central region of the key sheet tends to sag, leading to improper alignment and contact with the device housing, causing key buttons to shift from their predetermined position during assembly.
Innovation Solution
The electronic device incorporates a key sheet with pin holes and fitting protrusions on the upper case, ensuring the key sheet is securely attached without sagging, and integrates speaker packing portions with the key sheet for secure assembly and reduced part count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the key sheet is made from a single piece of elastic material without additional fixing structures, then the device complexity is reduced and manufacturing is simplified, but the key sheet sags in the central region and cannot maintain proper contact with the upper case
Solution Approach 1:
The key sheet is divided into multiple regions with pin holes at specific positions to create localized attachment points. These pin holes segment the otherwise continuous elastic material, allowing the central region to be held taut while the periphery maintains flexibility for key button operation.
Solution Approach 2:
Fitting protrusions on the upper case act as intermediary elements that insert into the pin holes of the key sheet. This intermediary mechanism provides a reliable connection between the upper case and the key sheet, preventing sagging while maintaining the simplicity of the overall structure.
2Manufacturing precision
If the key sheet is pressed firmly to prevent sagging, then alignment precision is improved, but the key buttons become difficult to press and key input operation is hindered
Solution Approach 1:
The key sheet is segmented into a central region with pin holes for secure attachment and peripheral regions with key buttons that remain flexible. This segmentation allows the central portion to be held firmly for alignment while the key button areas maintain the necessary elasticity for operation.
Solution Approach 2:
Different regions of the key sheet have different mechanical properties: the central region with pin holes provides structural stability and precise alignment, while the regions containing key buttons maintain high elasticity and flexibility to enable easy pressing. This local differentiation of material properties resolves the contradiction between firm attachment and operational ease.
Data Source
AI summary
An electronic device is provided with a device housing which includes an upper case and a lower case. A key input section is provided in the device housing and includes a key sheet disposed on an inner surface of the upper case. The key sheet has a plurality of key buttons exposed in an upper surface of the upper case and a plurality of pin holes provided at a plurality of positions excluding the key buttons. And, a plurality of fitting protrusions is provided on the inner surface of the upper case and inserted into and fitted in the pin holes of the key sheet.