Button Cover Structure for Large-Area Switch Actuation
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Solution Overview
Problem
Existing push buttons for switches, such as dome switches, require precise actuation, which can be challenging, especially for users with limited dexterity or in confined spaces, and often have complex constructions that are difficult to assemble.
Innovation Solution
A push button with an expanded actuatable area, covered by a button cover made of thermoplastic elastomer, featuring a ratio of actuatable area to active area of 10:1 to 200:1, and reinforced with ribs and a groove to facilitate easy actuation, allowing force transfer from any part of the actuatable area to the switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the push button uses a standard-sized switch button, then the device maintains a compact and simple structure, but the actuatable area is small requiring precise user input and reducing accessibility
Solution Approach 1:
The patent extends the actuatable area vertically by adding a button cover that protrudes from the device surface, creating a three-dimensional extension of the active area. This allows users to actuate the switch from a much larger surface area without requiring precise positioning, as the force can be applied anywhere on the extended button cover surface and still be transmitted to the switch.
2Ease of operation
If the push button expands the actuatable area multiple times larger than the switch button, then accessibility and ease of use are improved, but the device profile and construction complexity increase
Solution Approach 1:
The button cover is constructed from flexible polymeric material with specific Shore A hardness (72-85), allowing it to be pushed inward to actuate the switch. This flexibility enables the button cover to be relatively thin while still providing an expanded actuatable area, as the material itself deforms to transmit the actuating force without requiring a thick rigid structure.
Solution Approach 2:
The patent specifies precise material parameters (Shore A hardness of 72-85) to optimize the button cover's mechanical properties. This parameter control allows the material to be soft enough to provide a large compliant actuatable area while maintaining sufficient structural integrity to transmit force effectively, balancing the expanded area requirement with profile constraints.
3Reliability
If the push button incorporates ribs extending from the switch receiving area, then force transfer and actuation reliability are improved, but the manufacturing complexity increases
Solution Approach 1:
The button cover incorporates multiple ribs extending from the switch receiving area toward the perimeter, dividing the force transmission path into multiple structural zones. These ribs segment the polymeric material into regions that can independently manage stress distribution, improving force transfer reliability to the switch while maintaining manufacturability through standard injection molding techniques.
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 provides easier and more accessible actuation of switches, reducing the need for precise targeting and simplifying assembly, while maintaining structural integrity and ease of use.
Implementation Method 1
The button cover may be made of molded thermoplastic elastomer. The button cover may be formed of a polymeric material having a Shore A hardness of 72 or greater, 75 or greater, or 78 or greater, and 85 or less or 82 or less.
Data Source
AI summary
A device includes a device body comprising a first side; a switch disposed on the first side and comprising a button having a push direction and an active area perpendicular to the push direction; and a button cover. The button cover has a first major face facing outward and defining an actuatable area surrounded by a perimeter; and a second major face opposite of the first major face and facing the device. On the second major face are a switch receiving area constructed to contact the active area of the switch; and a plurality of ribs extending from the switch receiving area toward the perimeter.