Push Button Hinge Arm for Consistent Edge Tactile Feedback
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Solution Overview
Problem
Dome switches in push buttons for mobile computing devices often provide inconsistent positive tactile feedback, especially when depressed around the edges, and require additional electrical circuits when using dual-dome switches, which increases cost and complexity.
Innovation Solution
The implementation includes a push button design with a chassis, a dome switch, a button cap with button posts, and a hinge arm that spans the dome switch and button posts. The hinge arm is rotationally mounted to the chassis, allowing it to absorb torsional forces and maintain consistent tactile feedback across the button surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single dome switch is used in the push button, then the device complexity and cost are reduced, but the tactile feedback consistency deteriorates, especially when depressed around the edges
Solution Approach 1:
A hinge arm is introduced as an intermediary mechanical element between the button cap and the single dome switch. The hinge arm spans across the dome switch and is rotationally mounted to the chassis, acting as a mediator that translates button cap depression into dome switch actuation while maintaining consistent tactile feedback across different depression locations
Solution Approach 2:
The hinge arm adds a rotational dimension to the force transmission mechanism. Instead of direct vertical force transmission, the hinge arm converts the depression force into rotational motion around a hinge axis, which then actuates the dome switch. This dimensional transformation ensures that forces applied at different locations on the button cap are normalized before reaching the dome switch
2Reliability
If dual-dome switches are used to improve tactile feedback consistency, then the tactile feedback consistency improves, but the device complexity and electrical circuit requirements increase
Solution Approach 1:
The single dome switch is designed to handle multiple functions that would traditionally require separate switches. The hinge arm mechanism enables a single dome switch to provide consistent tactile feedback for the entire button cap surface, making the single dome switch a universal solution that replaces what would traditionally require multiple dome switches
Solution Approach 2:
The hinge arm combines multiple force transmission paths into a single actuation point. Instead of having separate dome switches for different button regions, the hinge arm merges the forces from various button cap locations into a unified mechanical action that actuates a single dome switch, thereby reducing electrical circuit complexity while maintaining tactile consistency
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 design achieves consistent edge performance by ensuring that the dome switch provides predictable and consistent positive tactile feedback regardless of where the force is applied on the button cap, without the need for dual-dome switches or additional electrical circuits.
Implementation Method 1
The hinge arm is rotationally mounted to the chassis, allowing it to absorb torsional forces and maintain consistent tactile feedback across the button surface
Implementation Method 2
dome switches (e.g., metal dome switches and polydomes) due to their compact size, positive tactile feedback, and ability to reliably withstand a large number of depression and release cycles
Data Source
AI summary
Dome switches can provide inconsistent positive tactile feedback, particularly when depressed around the edges of a corresponding push button as compared to depression at the middle of the push button. Various arrangements intended to render push buttons that incorporate one or more dome switches more consistent in providing positive tactile feedback, while maintaining a reasonable ease and cost of manufacturing, are discussed herein. A push button with consistent edge performance using a single dome switch incorporates a hinge arm that spans button posts. This reduces or eliminates rotation deflection of a button cap caused by the torsional forces on the push button created by depression forces applied by the user at an edge of the push button. As a result, the dome switch provides a predictable and consistent positive tactile feedback to the user similar to that achieved by a centrally applied depression force.