Touchsurface Assembly Buckling Elastic Component Lateral Motion

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Solution Overview

Problem

Existing pressable touchsurfaces in input devices, such as keyboards and touchscreens, often lack improved usability, flexibility, and tactile feedback, leading to suboptimal user experience due to limited vertical-lateral travel and snap ratio constraints.

Innovation Solution

A touchsurface assembly comprising a keycap, a base, and an elastic component that directionally buckles during press force application, allowing orthogonal lateral motion and enhanced tactile feedback by simulating greater vertical travel through planar translation, thereby improving usability and tactile feel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If traditional metal snap domes or rubber domes are used, then snapover haptic response is achieved, but device thickness and structural complexity increase

Engineering Contradiction:

Improvetactile feedbackVSAvoiddevice thickness

Core Design Contradiction:

Ease of operationVSLength of stationary object

Solution Approach 1:

The patent employs a thin flexible printed circuit board (FPC) as the elastic component that buckles during key press. This flexible film structure provides the necessary elastic response and tactile feedback without requiring thick mechanical domes, thereby reducing device thickness while maintaining haptic quality

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent replaces traditional mechanical snap dome structures with an elastic component based on controlled buckling mechanics. This substitution eliminates the need for complex mechanical assemblies while achieving similar or improved tactile response through material elasticity and geometric design

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If vertical key travel is increased, then tactile feedback is improved, but device thickness increases

Engineering Contradiction:

Improvetactile feedbackVSAvoiddevice thickness

Core Design Contradiction:

Ease of operationVSLength of stationary object

Solution Approach 1:

The patent introduces lateral translation motion in addition to vertical compression during key press. By allowing the keycap to move laterally as it compresses, the system creates a longer tactile path without increasing vertical thickness, effectively using a second dimension to extend the travel distance

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent employs dynamic motion where the keycap follows a curved trajectory combining vertical compression and lateral translation. This dynamic movement pattern allows the key to traverse a longer path during pressing while maintaining a compact vertical profile, improving tactile feedback without increasing device thickness

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If elastic component geometry is optimized for buckling, then planar translational responsiveness is achieved, but manufacturing precision requirements increase

Engineering Contradiction:

Improveplanar translational responsivenessVSAvoidelastic component geometry

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent optimizes the geometric parameters of the elastic component, including its length, width, thickness, and attachment point positions, to control the buckling behavior. By carefully selecting these parameters, the design achieves reliable planar translational responsiveness while keeping manufacturing tolerances within practical limits

Inventive Principle:

Principle #35Parameter changes

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 enhances tactile feedback and usability by increasing key travel distance perception and providing a more intuitive pressing experience through directional buckling, allowing for thinner, more flexible, and cost-effective device designs.

Implementation Method 1

The elastic component supports the keycap away from the base in an unpressed position, and directionally buckles during movement of the keycap toward a pressed position responsive to a press force

Methodology Applied

Scientific EffectBuckling:

Implementation Method 2

Upon release of the press force, the elastic component moves the keycap toward the unpressed position after release of the press force

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS9218927B2Touchsurface assembly with level and planar translational responsiveness via a buckling elastic component

Publication Date: 2015.12.22 SYNAPTICS INC

AI summary

Methods and apparatus for a touchsurface assembly such as a key assembly are described. The touchsurface assembly includes a keycap, a base and an elastic component coupled to the keycap and the base. The elastic component supports the keycap away from the base in an unpressed position, and directionally buckles during movement of the keycap toward a pressed position responsive to a press force. The press force moves the keycap in a press direction toward the pressed position, and the directionally buckling of the elastic component allows the keycap to move in a second direction orthogonal to the press direction. Upon release of the press force, the elastic component moves the keycap toward the unpressed position after release of the press force.