Piezo Force Sensing with Capacitive Touch
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Solution Overview
Problem
Existing input devices, such as track pads and touch sensitive displays, are limited in their ability to accurately determine the amount and location of force exerted by a user.
Innovation Solution
A system utilizing a transparent piezoelectric film that generates an electric charge in response to deformation, with electrodes on opposite surfaces to detect the charge and determine the force applied, combined with capacitive touch sensors to determine the location of touch events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional touch sensors are used, then touch location can be detected, but force amount cannot be accurately determined
Solution Approach 1:
The patent combines piezoelectric force sensing capability with capacitive touch location detection into a single integrated system. The piezoelectric film is positioned between the touch sensor and cover glass, allowing simultaneous detection of both touch location (via capacitive sensors) and force amount (via piezoelectric charge generation), thereby improving measurement precision without significantly increasing device complexity
Solution Approach 2:
The piezoelectric film serves multiple functions: it acts as both a force sensing element (generating charge proportional to applied force) and maintains compatibility with the capacitive touch sensor for location detection. This multi-functionality allows the system to detect both force amount and location using a unified sensing structure
2Measurement precision
If piezoelectric film is added to detect force, then force measurement capability is improved, but device structure becomes more complex
Solution Approach 1:
The patent uses a thin piezoelectric film as the force sensing element, which can be integrated between the touch sensor array and the cover glass. This thin-film approach minimizes the increase in device structure complexity while maintaining effective force measurement capability across the touch surface
Solution Approach 2:
The piezoelectric film is positioned in a different dimensional layer (between the touch sensor and cover glass) rather than replacing existing components. This spatial arrangement allows force sensing to be added without fundamentally restructuring the existing touch sensor architecture
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 detection of force and location of force applied to a device, allowing for accurate input recognition and multiple force measurements simultaneously.
Implementation Method 1
a piezoelectric film operably coupled to the cover material... a piezoelectric film for generating an electric charge in response to a deformation of the film
Data Source
AI summary
Systems for detecting an amount and/or location of a force applied to a device using a piezoelectric film are provided. One example system can include a transparent piezoelectric film for generating an electric charge in response to a deformation of the film. Electrodes positioned on opposite surfaces of the piezoelectric film can be used to detect the generated electric charge and determine an amount and/or location of force applied to the film based on the generated electric charge. In another embodiment, the system can include a capacitive touch sensor for determining a location of a touch event on the device.