Key Switch Dome Rubber Projection for Buckling Prevention
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Solution Overview
Problem
Conventional key switch devices using dome rubber experience uneven load distribution when the key top is tilted, leading to potential buckling deformation of the inner dome, which deviates the desired load characteristic and results in an uncomfortable operation feeling.
Innovation Solution
A key switch device featuring a dome rubber with a hemispherical bowl part and a projection at its center, which prevents buckling deformation by acting as a fulcrum and ensuring even load distribution, allowing the inner dome to deform without reversing and maintaining the desired load displacement characteristic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the key top is tilted during operation, then the operation flexibility is improved, but the load distribution becomes uneven causing buckling deformation of the inner dome
Solution Approach 1:
The projection at the center of the inner dome acts as an intermediary element that mediates the load transfer between the key top and the membrane sheet. When the key top is tilted, the projection ensures that the load is transferred through a defined path, preventing direct uneven loading on the inner dome that would cause buckling deformation.
Solution Approach 2:
The invention changes the structural parameters of the inner dome by adding a projection at its center. This structural modification alters how the inner dome responds to tilted key top operations, transforming the load distribution pattern from uneven to more uniform, thereby preventing buckling deformation while maintaining operational flexibility.
2Device complexity
If the inner dome deforms without the projection, then the device structure is simpler, but buckling deformation occurs causing deviation from desired load characteristic
Solution Approach 1:
The projection is added only at the critical local position (center) of the inner dome where load concentration occurs during tilted operation. This localized structural enhancement improves the overall load characteristic consistency without significantly increasing the overall device complexity, as the modification is confined to a specific region rather than the entire dome structure.
3Reliability
If the projection is added to prevent buckling, then the load characteristic is maintained, but the device structure becomes more complex
Solution Approach 1:
The projection is integrated into the inner dome as a single unified structure rather than being a separate component. The inner dome and projection are formed as one piece, merging the load-bearing dome with the load-distributing projection. This integration maintains load characteristic consistency while minimizing the increase in device complexity by avoiding additional parts or assembly steps.
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 a consistent and comfortable operation feeling by maintaining the desired load characteristic and preventing buckling deformation, even when the key top is tilted, thereby enhancing the operability of the key switch device.
Implementation Method 1
the operation force increases until a load which acts on the outer dome of the dome rubber reaches a buckling load of the outer dome. When the load which acts on the outer dome reaches the buckling load of the outer dome, the operation force decreases gradually with the increase in a keystroke.
Implementation Method 2
an outer dome that gives a reaction force according to elastic deformation to the key top
Data Source
AI summary
A reaction force generating member includes: a first dome that gives a reaction force to an operation member according to the depression of the operation member; and a second dome that includes a hemispherical bowl part disposed inside the first dome, and a projection projecting downward from the center of the bowl part and depressing a switch disposed below the operation member.