Double Pre-loaded Deflection Webs for Keypad Moisture Sealing
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Solution Overview
Problem
The miniaturization of handheld electronic devices has made it challenging to produce elastomeric or compliant layers for keyboards that provide effective tactile feedback and moisture protection, leading to issues with moisture ingress and damage to underlying components.
Innovation Solution
The implementation of a double pre-loaded deflection web structure, comprising a first deflection web for tactile response and a second, moisture-impermeable deflection web, which are pre-loaded and heat-staked to provide both tactile feedback and environmental sealing for the keys in a keypad module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If elastomeric or compliant layers are added to improve tactile feedback, then tactile feel is improved, but device size increases and moisture protection becomes compromised
Solution Approach 1:
The patent divides the deflection web into two separate functional layers: a first deflection web for tactile feedback and a second deflection web for moisture protection. This segmentation allows each layer to be optimized for its specific function without compromising the other, resolving the contradiction between tactile feedback and moisture protection.
Solution Approach 2:
The patent uses composite material structure by combining two different deflection webs with distinct properties. The first web provides tactile compliance while the second web provides moisture impermeability. This composite approach enables both tactile feedback and reliable moisture protection to coexist in the miniaturized keypad structure.
2Volume of moving object
If device size is reduced for portability, then portability is improved, but tactile feedback and moisture protection become insufficient
Solution Approach 1:
The patent resolves the size-tactile feedback contradiction by transitioning to a double-layer vertical structure. Instead of increasing horizontal size for better tactile feedback, the solution stacks two deflection webs vertically, each performing a specific function. This dimensional change allows adequate tactile feedback in a miniaturized horizontal footprint.
3Volume of moving object
If device size is reduced for portability, then portability is improved, but moisture protection becomes compromised
Solution Approach 1:
The patent segments the protection function by dedicating the second deflection web specifically to moisture protection. This separate layer ensures reliable sealing against moisture ingress even in the miniaturized device structure, resolving the contradiction between small size and effective moisture protection.
Solution Approach 2:
The patent employs thin film structures for the deflection webs, particularly the second web which provides moisture protection. These thin flexible films achieve effective moisture sealing without adding significant volume, enabling reliable protection in miniaturized devices.
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
This solution enhances tactile feedback and prevents moisture ingress, ensuring the reliability and longevity of the keypad components by providing a robust and sealed environment for the keys.
Implementation Method 1
When an actuation force is applied to the apex of the dome element, the dome element collapses to thereby complete an electrical circuit. The collapsing dome element provides a tactile feedback to the user
Implementation Method 2
The first and second deflection webs are pre-loaded and heat-staked to provide both tactile feedback and environmental sealing
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A keypad for an electronic device is provided and includes a substrate, a plurality of frets disposed with the substrate and a plurality of mechanical keys disposed with the substrate and arrayed in rows interleaved among the plurality of frets, at least one of the keys being deflectable toward a position at which a switch of a circuit is affected and a capacitive sensor layer disposed between the frets and the keys and the substrate to register movement of a capacitive element across the frets and the keys.