Inductive Force Sensing Trackpad with Stiffener Plate
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Solution Overview
Problem
Existing trackpads lack effective force detection and haptic feedback mechanisms, limiting their ability to provide nuanced input recognition and tactile user experiences.
Innovation Solution
A trackpad design incorporating a substrate, a stiffener plate, a circuit board with inductive elements for force sensing, and a spring mechanism that facilitates distance changes between components to detect applied force, combined with an actuator for haptic output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a hinged surface trackpad design is used, then tactile feedback can be provided, but force detection capability is limited and user input is constrained to particular sections
Solution Approach 1:
The patent replaces mechanical force sensing mechanisms with an inductive sensing system. An inductive element (coil) is positioned near a conductive target plate, and changes in inductance are measured as the trackpad surface deflects under applied force. This substitution enables full-surface force detection without mechanical contact points, resolving the contradiction between providing tactile feedback and enabling versatile force detection.
Solution Approach 2:
The trackpad surface is designed to serve multiple functions simultaneously: it provides tactile feedback through controlled deflection while also serving as a universal force sensing surface across its entire area. The inductive sensing system enables any location on the trackpad to detect force, making the device adaptable to various input locations and gestures, thus achieving both tactile feedback and comprehensive force detection capability.
2Measurement precision
If inductive elements are added to the circuit board, then force detection precision is improved, but device complexity increases
Solution Approach 1:
The inductive element (coil) is integrated directly into the circuit board layer structure, merging the sensing function with the existing circuit board substrate. This integration approach allows force detection precision to be improved while minimizing the increase in device complexity, as the inductive element becomes part of the circuit board's multi-layer construction rather than a separate component.
Solution Approach 2:
The patent optimizes the inductive element parameters (coil geometry, turns, spacing) and their positioning relative to the conductive target plate to achieve high force detection precision. By carefully controlling these parameters during manufacturing, accurate force sensing is achieved without requiring overly complex circuit board designs or additional processing steps.
3Reliability
If spring mechanism is implemented, then force sensing capability is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent employs a flexible circuit board that can deflect under applied force, eliminating the need for separate spring mechanisms. The flexible circuit board itself serves as the compliant element that enables force sensing through its controlled deflection, which is detected by the inductive sensing system. This approach enhances force sensing capability while simplifying manufacturing, as the flexible circuit board is a standard component that can be integrated into the existing trackpad assembly without additional spring components.
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
Enables precise force detection and haptic feedback, enhancing user input recognition and providing a more immersive tactile experience by leveraging inductive sensing and spring-based mechanics.
Implementation Method 1
force sensing circuitry configured to detect force applied to the substrate, the force detected using the inductive element
Implementation Method 2
a spring between the stiffener plate and the housing, the spring facilitating a change in distance between the stiffener plate and the housing based on a force applied to the substrate
Data Source
AI summary
According to one aspect, a trackpad includes: a substrate; a stiffener plate; a circuit board between the substrate and the stiffener plate, the circuit board comprising position detecting circuitry configured to detect a position of an object adjacent the substrate, the circuit board including an inductive element; a grounding element that electrically connects the stiffener plate and the circuit board to each other; and force sensing circuitry configured to detect force applied to the substrate, the force detected using the inductive element.