Thin Profile Sealed Button Assembly Housing Integration
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Solution Overview
Problem
Conventional button assemblies in electronic devices suffer from reduced operational life due to abrasion of electrical switches and compromised seals, leading to intrusion of foreign matter, which is exacerbated by the need for specialized machining of the device housing for fastening features.
Innovation Solution
A sealed button assembly that mechanically couples a button cap to an electrical switch via a push rod, using a button retainer and bracket that clamps around a counterbore or shelf in the housing, with seals to prevent foreign matter intrusion, eliminating the need for specialized machining and maintaining a thin profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the protrusion is formed as an integral part of the button cap, then the button assembly structure is simplified, but the electrical switch surface is abraded and operational life is reduced
Solution Approach 1:
The button assembly is divided into separate functional components: the button cap, the protrusion (made from wear-resistant material), and the electrical switch. The protrusion is detachably coupled to the button cap rather than being integral, allowing the wear-prone interface between protrusion and switch to be isolated. This segmentation enables the protrusion to be replaced when worn without replacing the entire button cap, thereby extending operational life while maintaining structural simplicity.
2Ease of operation
If off-axis force is applied to the button cap, then the button can be actuated, but torque is applied to the protrusion causing lateral abrasion of the electrical switch
Solution Approach 1:
A protrusion made from wear-resistant material is introduced as an intermediary between the button cap and the electrical switch. This intermediary component absorbs the lateral abrasion caused by off-axis forces, protecting the electrical switch surface. The protrusion is designed to be replaceable, allowing it to serve as a sacrificial element that can be renewed when worn, thus eliminating the harmful abrasion effect on the switch while maintaining ease of button actuation.
3Duration of action of moving object
If repeated abrasion occurs on the electrical switch, then the button assembly can still function, but seal effectiveness is reduced and foreign matter intrusion increases
Solution Approach 1:
The protrusion is made from wear-resistant material that serves as a protective barrier before the electrical switch is exposed to abrasion. This prior cushioning prevents direct contact between the switch surface and the button cap during off-axis actuation. By anticipating and preventing the abrasion problem before it occurs, the seal effectiveness is maintained and foreign matter intrusion is prevented, while the button assembly continues to function throughout the extended life of the wear-resistant protrusion.
4Strength
If specialized machining is performed on the housing for fastening features, then the button assembly can be securely fastened, but manufacturing time and cost increase
Solution Approach 1:
The fastening features are extracted from the housing and relocated to the button assembly itself. Instead of machining specialized features into the housing, the button cap incorporates integrated fastening elements that engage with corresponding features on the housing. This extraction eliminates the need for time-consuming specialized machining of the housing while maintaining secure fastening strength, thereby reducing manufacturing time and cost without compromising attachment reliability.
Data Source
AI summary
A sealed button assembly including a button cap, a push rod, a button retainer, and a bracket is described. The bracket can couple to the button retainer which itself can interlock with the button cap and push rod through a counterbore, the counterbore being defined in a sidewall of the housing of an electronic device.