Switch Link Mechanism Stabilizing Key Top Movement

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Solution Overview

Problem

Conventional switch mechanisms using gear-shaped link members face instability in parallel and vertical movement due to shallow meshing at key top limit positions, making it difficult to maintain accurate tooth shape and smooth operation, especially during downsizing.

Innovation Solution

A switch design featuring a pair of link members with a coupling portion that turnably couples them, allowing the coupling-portion-side supported portion to slide perpendicular to the base and operation unit, stabilizing the operation unit's direction when moved in a contacting/separating direction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If gear-shaped link members with meshing teeth are used to guide key top movement, then the key top can move in parallel and vertical directions, but meshing becomes shallow at upper and lower limit positions causing unstable movement

Engineering Contradiction:

Improveparallel and vertical movement of key topVSAvoidstability of key top movement at limit positions

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent extracts the meshing teeth from the link member structure entirely, replacing the gear-shaped mechanism with a sliding mechanism. The link members become simple elongated bodies without teeth, eliminating the shallow meshing problem at limit positions while maintaining the guiding function through the sliding interface between link members and the key top.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using positive meshing engagement (teeth interlocking) to guide movement, the patent inverts the approach by using a sliding interface where the link members move relative to each other and to the key top. This inversion transforms the engagement mechanism from interlocking teeth to sliding surfaces, ensuring stable contact at all positions including limit positions.

Inventive Principle:

Principle #13The other way round (Inversion)

2Adaptability or versatility

If two gear shapes are overlapped for link members, then meshing is ensured, but tooth module must be reduced for downsizing which makes it difficult to ensure accuracy in tooth shape

Engineering Contradiction:

Improvedownsizing capabilityVSAvoidaccuracy in tooth shape

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent removes the complex tooth geometry from the link members, replacing it with simple elongated sliding surfaces. This extraction eliminates the need for precise tooth shaping while maintaining the guiding and supporting functions, enabling downsizing without compromising manufacturing precision.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the geometric parameters of the link members from gear-shaped with specific tooth modules to simple elongated bodies with sliding surfaces. This parameter change simplifies the geometry, making it easier to manufacture with high precision at smaller sizes while maintaining functional performance.

Inventive Principle:

Principle #35Parameter changes

3Length of stationary object

If meshing between teeth is shallow at limit positions, then the mechanism achieves low profile, but parallel and vertical movement becomes unstable

Engineering Contradiction:

Improveprofile height of switch mechanismVSAvoidstability of key top movement

Core Design Contradiction:

Length of stationary objectVSStability of the object's composition

Solution Approach 1:

By removing the toothed gear structure entirely, the patent eliminates the shallow meshing issue that occurs at limit positions in compact gear mechanisms. The sliding-based link member structure maintains stable contact and guiding throughout the full range of motion while achieving a low profile suitable for compact switch designs.

Inventive Principle:

Principle #2Taking out (Extraction)

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 configuration ensures the operation unit remains oriented in a certain direction, such as parallel to the base, while reducing backlash and abrasion, and maintaining stability even when pressed from any portion, enhancing the switch's reliability and accuracy.

Implementation Method 1

the coupling-portion-side supported portion slides with respect to one of the base and the operation unit in a direction substantially perpendicular to the contacting/separating direction and in a direction substantially perpendicular to a rotational axis of the pair of link members

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS11410822B2Switch and keyboard

Publication Date: 2022.08.09 OMRON CORP

AI summary

Embodiments disclosed herein describe a base, an operation unit that moves in a contacting/separating direction with respect to the base in response to an external force, and a pair of link members turnably coupled to each other by a coupling portion and configured to guide movement of the operation unit in the contacting/separating direction. The pair of link members includes a first curved portion and a second curved portion that are supported on the base, and a first rotary spindle and a second rotary spindle that are supported on the operation unit. When the operation unit moves in the contacting/separating direction with respect to the base, the first curved portion and the second curved portion slide with respect to the base in a direction substantially perpendicular to the contacting/separating direction and in a direction substantially perpendicular to a turning shaft of the pair of link members.