Mechanical Flexural Trackpad for Uniform Click Feedback
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Solution Overview
Problem
Existing clickable trackpads face challenges in providing consistent tactile feedback across the entire surface due to varying force requirements for registering a click, especially near mechanical hinged mechanisms, and haptic trackpads are costly.
Innovation Solution
A mechanical flexural parallel motion trackpad design using a printed circuit board assembly, touch sensor, switches, and torsion bars with flexure mechanisms to allow consistent click feedback across the entire surface without mechanical hinged mechanisms, relying on a dome switch for actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a mechanical hinged mechanism is used in clickable trackpads, then the trackpad can register clicks, but the force requirements vary across the surface especially near the hinged mechanism
Solution Approach 1:
The trackpad surface is divided into multiple zones with independent flexure mechanisms. Each zone has its own flexure elements that can be independently tuned to provide uniform force characteristics across different regions, eliminating the variation problem near hinged mechanisms.
Solution Approach 2:
The flexure mechanisms use adjustable parameters such as flexure element stiffness, length, and positioning to optimize the force characteristics for each region of the trackpad surface, enabling consistent click registration across the entire surface.
2Ease of operation
If haptic trackpads are used to provide consistent tactile feedback, then uniform click feel is achieved, but manufacturing cost increases
Solution Approach 1:
The flexure mechanisms themselves provide the haptic feedback through their elastic deformation during click registration. The flexure elements naturally return to their original position after deformation, providing tactile feedback without requiring separate haptic actuators or motors.
Solution Approach 2:
The patent replaces complex electronic haptic actuators with simple mechanical flexure elements that provide tactile feedback through their inherent elastic properties. This substitution dramatically reduces manufacturing cost while maintaining uniform tactile feedback.
3Ease of operation
If complex haptic mechanisms are added to trackpads, then consistent tactile feedback is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The flexure mechanisms serve multiple functions simultaneously: they provide structural support for the touch sensor, enable click registration through elastic deformation, and generate tactile feedback through their inherent elasticity. This multi-functionality eliminates the need for separate haptic components.
Solution Approach 2:
The flexure elements are designed to be simple, reusable components that can be easily manufactured and replaced. Their elastic nature allows them to be compressed during click registration and automatically recover to their original position, providing feedback without complex recovery mechanisms.
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 design provides uniform tactile feedback and click feel across the trackpad surface, reducing manufacturing complexity and cost by eliminating the need for haptic devices while maintaining a thin form factor.
Implementation Method 1
a first set of flexural parallel motion brackets to constrain motion of a first distal end of the first torsion bar to rotation about a first virtual axis
Implementation Method 2
a first torsion bar, a second torsion bar... to rotationally link the first distal ends of the first and second torsion bars
Data Source
AI summary
Clickable trackpad designs generally aim to achieve a thin form factor with a minimized footprint that provides consistent user perception of click feel at scale within cost constraints. The clickable trackpad designs found herein adopt a mechanical depression mechanism that allows a user to register a click at any point on the trackpad surface with little variance in the depression force required to register the click. This provides a consistent click feel for the user. Further consistency of the click feel is achieved by establishing simultaneous travel of the entire trackpad surface, no matter where the click force is applied. This motion is a downward translation of the trackpad surface. An end user may press at any location of the trackpad surface to achieve a push button input (or click).