Modular Keyboard Assembly Alignment via PCB Ribs
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Solution Overview
Problem
Current keyboard assembly designs face challenges in aligning key-mats with keyboard PCBs, especially for larger devices, due to high tolerances in plastic molding, leading to gaps and reduced flexibility in button layout and modular design.
Innovation Solution
The implementation of alignment means, such as alignment pins and ribs, allows for precise alignment of key-mat strips to the keyboard PCB, enabling tighter spacing between buttons and facilitating a modular design with flexible button layouts and improved tactile feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If key-mat is aligned to housing using hooks and posts, then assembly is simple, but alignment accuracy between key-mat and PCB deteriorates due to plastic molding tolerances
Solution Approach 1:
The patent introduces an intermediate alignment structure consisting of alignment ribs on the PCB and corresponding alignment grooves on the key-mat. This intermediary mechanism mediates between the housing alignment system and the key-mat positioning, ensuring precise alignment independent of housing tolerances. The alignment ribs extend through the housing to directly engage with the key-mat, creating a dedicated alignment pathway that isolates the key-mat positioning from housing manufacturing variations.
2Stability of the object's composition
If key-mat is rigidly held at perimeter in stretched condition, then key-mat stability is improved, but button spacing tolerances deteriorate due to inherent rubber material tolerances
Solution Approach 1:
The patent segments the key-mat into multiple independent key regions, each with its own alignment features. Instead of relying on the entire key-mat perimeter to maintain positioning, each key section is independently aligned through the rib-groove mechanism. This segmentation allows localized precision without requiring uniform tension across the entire stretched key-mat, thereby improving button spacing tolerances while maintaining overall stability.
3Ease of manufacture
If press buttons are aligned towards housing, then assembly process is simplified, but button layout flexibility deteriorates due to tooling constraints
Solution Approach 1:
The alignment rib structure serves multiple functions: it provides alignment, positioning, and mechanical attachment all in one feature. The ribs can be configured in various patterns to accommodate different button layouts without changing the fundamental alignment mechanism. This universal alignment approach allows the same basic structure to support diverse key arrangements, improving layout flexibility while maintaining assembly simplicity.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3~4
AI summary
A key-board assembly (10) is described that has a key-mat and a keyboard PCB (3) aligned with respect to each other instead of first to a housing of an input device. First, such alignment is achieved by adding pins (6) to the key-mat that fit tightly in holes (5) of the PCB. Secondly the key-mat has hooks (14) that can be clicked around the PCB and/or ribs (4) around the edges/carve-outs of the PCB that hold to the PCB with tight tolerances.