Bellows-like Spring Switch Resolving Height and Contact Pressure Trade-off
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Solution Overview
Problem
Conventional switches face limitations in reducing height dimension while maintaining desired stroke and contact pressure, and are difficult to mass-produce with complex shapes and high dimensional accuracy due to the use of coil springs.
Innovation Solution
A super-thin switch design featuring a bellows-like spring member with elastic arm portions, where one arm serves as a sliding movable contact and the other as a rotationally movable contact, eliminating the need for coil springs and allowing for adjustable stroke and contact pressure through elastic deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a coil spring is used to secure contact pressure, then the desired contact pressure is achieved, but the height dimension cannot be reduced
Solution Approach 1:
The patent changes the spring mechanism from a traditional coil spring to a bellows-like spring portion with elastic arm portions. This structural parameter change allows the spring to provide sufficient contact pressure while having a compressed height of 0.7 mm or less, resolving the contradiction between maintaining contact pressure and reducing height dimension.
Solution Approach 2:
The bellows-like spring portion incorporates curved, accordion-like structures that enable efficient elastic deformation in a compact form. The curved geometry of the bellows allows the spring to store and release mechanical energy effectively while maintaining a low profile, thus achieving both contact pressure and reduced height.
2Length of moving object
If a bellows-like spring member is used to reduce height dimension, then a low height dimension is achieved, but the desired stroke and contact pressure may not be secured
Solution Approach 1:
The spring member is segmented into a bellows-like spring portion and two elastic arm portions. This segmentation allows each part to perform its specific function: the bellows portion provides compactness and initial elasticity, while the elastic arm portions extend the stroke and maintain contact pressure, thereby ensuring reliable operation despite the reduced height.
Solution Approach 2:
The spring member functions as a composite structure combining the bellows-like spring portion with elastic arm portions. This composite design integrates the advantages of both structures: the compactness and elasticity of the bellows with the extended reach and contact stability of the elastic arms, ensuring both desired stroke and contact pressure are achieved.
3Force
If coil springs with complicated shapes are used, then the desired contact pressure is achieved, but mass production with high dimensional accuracy is difficult
Solution Approach 1:
The patent adopts a bellows-like spring structure that can be manufactured using standard press working processes, unlike complicated coil spring geometries. This parameter change in structural design makes the spring member suitable for mass production while maintaining high dimensional accuracy and consistent contact pressure performance.
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 design achieves a low height dimension with desired stroke and contact pressure, provides a soft operation feel, and reduces stress concentration and fatigue failure through reinforcing ribs, resulting in a long-lasting switch.
Implementation Method 1
the bellows-like spring portion of the spring member is elastically deformed
Implementation Method 2
an operation lever including an operation rib, which comes in contact with the one elastic arm portion of the spring member, and rotationally supported on the base
Data Source
AI summary
A switch has a base having a frame portion disposed integrally with an outer peripheral portion of an upper surface of the base, a common fixed contact disposed at a corner of inside surfaces of the frame portion, and a fixed contact disposed on an inside surface of the base opposite to the common fixed contact, a spring member having elastic arm portions extending respectively from both ends of a bellows-like spring portion, wherein a free end portion of one of the elastic arm portions serves as a sliding movable contact, wherein a free end portion of another of the elastic arm portions serves as a rotationally movable contact, and wherein the rotationally movable contact is positioned so as to be in contact with the common fixed contact of the base, and an operation lever including an operation rib.