Coaxial Haptic Force Sensing Unit with Capacitance Detection
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Solution Overview
Problem
Information handling systems lack effective mechanisms for independent haptic force sensing, which is crucial for providing tactile feedback and accurately measuring forces applied to touch surfaces, such as in touch panel devices.
Innovation Solution
A coaxial independent haptic force sensing unit is implemented, comprising a face plate, a force-feedback device with a PCB, a piezo disc, and a touch panel circuit. The force-feedback device includes a metallic ring and a piezoelectric wafer, where the touch panel circuit determines capacitance between the rings to calculate forces and trigger haptic feedback responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a touch panel device uses conventional force sensing mechanisms, then the device structure can be simpler, but the force measurement precision and haptic feedback capability are insufficient
Solution Approach 1:
The patent combines the force sensing function and haptic feedback function into a single integrated force-feedback device. The PCB with first metallic ring, piezoelectric disc with second metallic ring, and touch panel circuit work together as one unified component that both detects force and provides haptic feedback, eliminating the need for separate sensing and actuation mechanisms.
Solution Approach 2:
The force-feedback device serves multiple functions simultaneously: it acts as a force sensor to detect applied pressure, a capacitor to measure force magnitude through capacitance changes, and a haptic actuator to provide tactile feedback to the user. This multi-functionality resolves the contradiction by achieving precise force measurement without requiring additional dedicated components.
2Reliability
If the PCB moves closer to the piezo disc to detect force, then the force sensing capability improves, but the device structure becomes more complex
Solution Approach 1:
The patent replaces complex mechanical force sensing mechanisms with an electrical capacitance-based detection system. Instead of using mechanical linkages or strain gauges that would add structural complexity, the system uses the capacitance change between two metallic rings to detect force, providing reliable sensing with simpler structure.
Solution Approach 2:
The patent introduces an elastic ring as an intermediary element between the PCB and the piezoelectric disc. This elastic ring allows the PCB to move closer to the piezo disc in response to force while maintaining a flexible, simple structure. The elastic ring mediates the force transmission and enables the capacitance-based detection mechanism without requiring complex mechanical linkages.
3Measurement precision
If the touch panel circuit determines capacitance between metallic rings to calculate force, then the force measurement accuracy improves, but the circuit complexity increases
Solution Approach 1:
The touch panel circuit utilizes the inherent capacitance between the two metallic rings as a self-contained sensing mechanism. The circuit doesn't require external complex measurement systems; it simply measures the capacitance change that naturally occurs as the PCB moves relative to the piezoelectric disc in response to applied force, providing accurate force measurement with minimal circuit complexity.
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 solution enables precise force detection and haptic feedback, enhancing user interaction by providing tactile responses to forces applied on the touch panel device, improving user experience and system responsiveness.
Implementation Method 1
The piezoelectric wafer may be actuated by a voltage to provide a haptic feedback response
Implementation Method 2
the touch panel circuit may determine a capacitance between the first metallic ring and the second metallic ring, determine a force associated with the contact based upon the capacitance
Data Source
AI summary
A touch panel device includes a face plate, a force-feedback device, and a touch panel circuit. The face plate receives at a first surface a contact with the face plate. The force-feedback device includes a PCB affixed by a first surface of the PCB to a second surface of the face plate. The PCB includes a first metallic ring on a second surface of the PCB. The piezo disc includes a piezoelectric wafer and a second metallic ring. The piezo disc is adjacent to the second surface of the PCB. The touch panel circuit is coupled to the first metallic ring, the second metallic ring, and the piezoelectric wafer. The touch panel circuit determines a capacitance between the first metallic ring and the second metallic ring, determines a force associated with the contact based upon the capacitance, and triggers a haptic feedback response in the piezoelectric wafer.