Keypad Apparatus Using Collapsible Dome Switches

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Portable electronic devices face challenges in reducing their size due to the bulkiness caused by electrical switch assemblies soldered to circuit boards, which increases the dimensional envelope and costs associated with soldering.

Innovation Solution

The use of collapsible dome switches with a carrier that electrically couples to the circuit board via conductive traces and flexible fingers, eliminating the need for fasteners like solder, and employing Laser Direct Structuring for conductive contact and trace formation on a plastic carrier.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electrical switch assemblies are soldered to circuit boards, then reliable electrical connection is achieved, but the dimensional envelope of the electronic device increases

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoiddimensional envelope

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The patent replaces the mechanical soldering process with a dome switch mechanism that uses elastic deformation and contact pressure to establish electrical connections. The dome switch's flexible contact legs press against the circuit board contacts, eliminating the need for solder while maintaining reliable electrical connection through mechanical pressure and elastic recovery.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The dome switch structure utilizes three-dimensional elastic deformation of the dome and its contact legs to achieve reliable electrical connection. The dome's radial and axial deformation provides contact force in multiple directions, allowing compact integration without requiring the extended flat layout typical of soldered assemblies.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Strength

If electrical switch assemblies are soldered to circuit boards, then secure mechanical attachment is achieved, but assembly costs increase

Engineering Contradiction:

Improvemechanical attachment strengthVSAvoidassembly cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent replaces the soldering process with a mechanical dome switch assembly that achieves both electrical connection and mechanical attachment through the same component. The dome switch's contact legs provide both electrical conductivity and mechanical retention, eliminating the need for separate soldering operations and reducing assembly complexity and cost.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The dome switch integrates multiple functions into a single component: it provides electrical connection, mechanical attachment, and tactile feedback simultaneously. The contact legs serve both as electrical conductors and as mechanical retention elements, merging the functions of electrical and mechanical systems into one unified structure that simplifies manufacturing.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If physical keys with electrical switch assemblies are used, then reliable key input function is achieved, but the device size increases

Engineering Contradiction:

Improvekey input functionVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The dome switch is nested within the key cap structure, with the key cap serving as both the user interface element and the housing for the dome switch mechanism. The dome switch contacts are integrated into the key cap assembly, allowing the key input function to be achieved in a compact nested configuration rather than requiring separate components.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The dome switch utilizes thin flexible contact legs that can deform elastically to provide tactile feedback and reliable electrical connection. These thin-film flexible contacts enable the key mechanism to function with minimal thickness, reducing the overall volume required for each key while maintaining reliable input function.

Inventive Principle:

Principle #30Flexible shells and thin films

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 solution reduces the overall dimensional envelope of electronic devices, decreases assembly costs by avoiding soldering, and facilitates a more compact and cost-effective keypad apparatus.

Implementation Method 1

a dome switch collapses toward a conductive contact formed or printed on the carrier

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

employing Laser Direct Structuring for conductive contact and trace formation on a plastic carrier

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentUS9087663B2Keypad apparatus for use with electronic devices and related methods

Publication Date: 2015.07.21 MALIKIE INNOVATIONS LTD

AI summary

A keypad apparatus and related methods are disclosed herein. An example keypad apparatus includes an electrical switch and a carrier composed of a plastic resin. The carrier has conductive traces printed thereon to couple the electrical switch to a circuit board via interference.