Double Pre-loaded Deflection Webs for Keypad Moisture Protection
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Solution Overview
Problem
Miniaturization of handheld electronic device keypads has led to challenges in producing elastomeric layers that fit properly, resulting in moisture ingress and damage to underlying components due to their small size.
Innovation Solution
The implementation of a double pre-loaded deflection web structure, comprising a first deflection web for tactile feedback and a second, moisture-impermeable deflection web for protection, which are pre-loaded during assembly to ensure proper fit and functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If elastomeric or compliant layers are added to dome elements to improve tactile feedback, then tactile feel is enhanced, but the layers become too small to fit properly with keys and structural elements, leading to moisture ingress
Solution Approach 1:
The patent divides the deflection mechanism into separate components: dome elements for tactile feedback and a distinct elastomeric layer for moisture protection. This segmentation allows each component to be optimized independently - the dome elements provide tactile response while the elastomeric layer forms a continuous moisture barrier without being compromised by the small size of individual key components.
Solution Approach 2:
The elastomeric layer is positioned to surround and protect the underlying dome elements and circuit board components. The layer is configured to extend beyond the keys and structural elements, creating a nested protective configuration where the elastomeric material forms an outer barrier that envelops the sensitive internal components.
2Volume of moving object
If the size of handheld electronic devices is reduced for improved portability, then device compactness is improved, but the size of keypad components decreases, making it difficult to produce properly fitting elastomeric layers
Solution Approach 1:
By separating the tactile function (dome elements) from the protective function (elastomeric layer), the patent enables the elastomeric layer to be designed as a continuous barrier that spans across multiple keys and structural elements. This segmentation allows the layer to maintain adequate size and continuity for effective moisture protection even in miniaturized device configurations.
Solution Approach 2:
The elastomeric layer serves multiple functions simultaneously: it provides moisture protection, structural support, and sealing between components. This multi-functionality allows a single component to address multiple challenges of miniaturization without requiring proportionally smaller dimensions for each specific function.
3Device complexity
If simple sphere segment dome elements are used, then device simplicity is maintained, but tactile feedback is not noticeable
Solution Approach 1:
The patent combines rigid dome elements with a compliant elastomeric layer to create a composite structure. The dome elements provide structural integrity and switching functionality, while the elastomeric layer adds compliance and enhances tactile feedback. This composite approach improves tactile noticeability without significantly increasing overall device complexity.
Solution Approach 2:
The elastomeric layer is strategically positioned at specific locations where tactile feedback is needed - particularly at the key surfaces and contact points. This localized application of compliant material enhances tactile quality precisely where users interact with the keypad, while maintaining structural simplicity in other areas of the device.
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 configuration enhances tactile feedback while preventing moisture ingress, ensuring the reliability and durability of the keypad components.
Implementation Method 1
a first deflection web between the keys and the substrate and configured to provide the keys with a tactile response
Implementation Method 2
double pre-loaded web deflection structure includes a substrate, an array of dome elements, an array of mechanical keys, a first deflection web, and a second deflection web; the first and second webs being pre-loaded at non-key locations in a deflection direction
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A keypad for an electronic device is provided and includes a substrate comprising an array of dome elements, an array of frets, an array of mechanical keys disposed in rows interleaved between the frets, a first deflection web supportively disposed adjacent to the substrate and a second deflection web disposed between the frets and the keys and the first deflection web. The substrate is configured to pre-load the first and second deflection webs toward the keys.