Eighth-Order Dome Spring Reducing Wear in Push Button Switches
Solution Overview
Problem
Conventional dome-shaped springs used in push button switches experience wear and conductive failure due to repeated movements, leading to a larger size and unreliable tactile click action.
Innovation Solution
A dome-shaped spring with a neutral plane defined by an even function of eighth-order or more, where specific angles between the neutral plane and the substrate at inflection points reduce radial displacement and wear, combined with a switch design that includes stationary contacts and a movable contact for reliable buckling action.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional aspheric dome-shaped spring with sixth-order even function is used, then the size is reduced and click feel is improved, but wear occurs at the circumferential edge and stationary contacts due to radial displacement during repeated movements
Solution Approach 1:
The patent changes the mathematical order of the even function from sixth-order to eighth-order or higher to define the neutral plane shape. This parameter change in the function order modifies the curvature characteristics of the dome-shaped spring, reducing radial displacement at the circumferential edge during buckling movements, thereby minimizing wear on both the circumferential edge and stationary contacts while maintaining the compact size and click feel
Solution Approach 2:
The patent optimizes the curvature distribution of the neutral plane by using an eighth-order or higher even function. This creates a more refined aspheric shape with controlled curvature variations that reduce the radial displacement component during operation, decreasing friction and wear at the contact points between the circumferential edge and stationary contacts
2Volume of moving object
If the dome-shaped spring is made smaller, then the switch size is reduced, but the reliability of tactile click action may be compromised
Solution Approach 1:
By increasing the order of the even function to eighth-order or higher, the patent achieves a more precise control over the deformation characteristics of the dome-shaped spring. This allows the spring to maintain optimal buckling behavior and click feel even at reduced sizes, as the higher-order function provides better control over the stress distribution and deformation profile throughout the structure
Solution Approach 2:
The refined aspheric shape defined by the eighth-order or higher even function creates optimal curvature distribution that enhances the buckling action. The controlled curvature variations ensure that the spring maintains its tactile click characteristics while being downsized, as the shape optimization compensates for the reduced dimensions
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 enables downsizing of the dome-shaped spring and switch while maintaining a reliable tactile click action, reducing wear on the circumferential edge and stationary contacts, thus enhancing durability and performance.
Implementation Method 1
The dome-shaped spring becomes deformed by applying an acting load F onto the movable contact 21a of the dome-shaped spring 21 from vertically upside by a user. By continuing application of the load F, a click action occurs by buckling of the dome-shaped spring 21
Implementation Method 2
By continuing application of the load F, a click action occurs by buckling of the dome-shaped spring 21
Data Source
AI summary
Provided is a dome-shaped spring for placing on a substrate having stationary contacts, and a circumferential edge of the dome-shaped spring is continuously in contact with the stationary contacts. At least a part of a neutral plane has a shape defined by an even function of at least eighth-order. Angle α of the neutral plane of the dome-shaped spring to the substrate at a second inflection point that exists at a second-positioned inflection point from the circumferential edge, angle β of the neutral plane to the substrate at a first inflection point, and angle γ of the neutral plane at the circumferential edge of the dome-shaped spring to the substrate satisfy following inequalities of αβ and βγ.