Parallel-Motion Trackpad for Uniform Click Force Feedback
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Solution Overview
Problem
Conventional trackpads often lack intuitive and comfortable feedback mechanisms, especially in portable devices where mechanical buttons are undesirable due to space constraints, and 'diving board' designs have inconsistent click forces across the surface, detracting from user experience.
Innovation Solution
A trackpad design featuring a touch plate with a support mechanism that translates vertically without rotation, using a pivotable mechanism with rotatable wings to ensure equal downward force requirements and parallel motion across the surface, accompanied by a switch for tactile feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a diving board design is used for the trackpad, then the structure is simple and space-efficient, but the click force becomes inconsistent across the surface
Solution Approach 1:
The support mechanism is divided into multiple independent arms (first arm, second arm, third arm) that are pivotally connected to the touch plate at different locations. Each arm independently supports a portion of the touch plate, allowing the system to achieve uniform click force across the surface while maintaining structural simplicity. This segmentation resolves the contradiction by distributing the support function across multiple simple components rather than requiring a complex monolithic structure.
Solution Approach 2:
The patent combines multiple support arms with a common pivotal connection point to the substrate, merging their functions into a unified support system. This merging allows the trackpad to maintain parallel motion during actuation while using simple, space-efficient arm structures. The combined system achieves consistent click force across the surface without requiring each individual arm to be complex.
2Ease of operation
If mechanical buttons are used for input, then tactile feedback is intuitive and comfortable, but space is consumed and mechanical components increase complexity
Solution Approach 1:
The patent replaces traditional mechanical buttons with a capacitive touch sensor system that detects finger contact through electrical field changes. This substitution eliminates the need for separate mechanical button components while maintaining tactile feedback through the actuation of the touch plate. The touch sensor integrated into the touch plate provides button-like functionality without the space and complexity of dedicated mechanical buttons.
Solution Approach 2:
The touch plate serves multiple functions: it acts as both the input surface for gesture recognition and as the actuator that provides tactile feedback when pressed. The same structural component (touch plate) that enables gesture input also provides the mechanical feedback sensation, eliminating the need for separate button mechanisms. This multi-functionality reduces overall device complexity while maintaining intuitive tactile feedback.
3Device complexity
If the touch plate is allowed to rotate during actuation, then the support mechanism can be simpler, but the click force distribution becomes uneven across the surface
Solution Approach 1:
The support mechanism is designed to dynamically adapt to the location of applied force on the touch plate. When force is applied at any location, the pivotable arms automatically adjust their angles and positions to maintain parallel motion of the touch plate. This dynamic adjustment ensures uniform click force distribution across the entire surface while keeping the mechanism itself relatively simple, as no complex pre-adjustment or calibration is required.
Solution Approach 2:
The patent changes the geometric parameters of the support mechanism (arm lengths, pivot points, connection locations) to achieve parallel motion during actuation. By carefully selecting these parameters, the system ensures that the touch plate moves uniformly without rotation regardless of where it is pressed. This parameter optimization allows the mechanism to maintain simplicity while achieving precise force distribution.
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
Provides consistent tactile feedback and equal click force across the trackpad surface, enhancing user experience and comfort by maintaining parallel motion and reducing power and cost requirements.
Implementation Method 1
a switch to transduce movement of the touch plate along the central axis
Implementation Method 2
a touch sensor to detect a user touch on the top surface
Data Source
AI summary
An input device includes a touch plate having a central axis and a top surface with three outer points evenly spaced away from the central axis. A touch sensor is used to detect a user touch on the top surface at the first outer point, and a support mechanism supports the touch plate and is configured to translate the touch plate at the second and third outer points upon application of the user touch and translation of the touch plate at the first outer point. Translation of the three outer points is substantially equal along the central axis.