Electroactive Polymer Haptic Layer for Transparent Touch Feedback
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Solution Overview
Problem
Existing haptic devices for touch-sensitive display devices face challenges in providing immediate, delicate, and varied tactile feedback due to limitations in vibration strength, frequency modulation, response speed, and durability, particularly when trying to transmit various textures and tactile feelings, and are often opaque, making them unsuitable for placement above display panels.
Innovation Solution
A touch-sensitive element with an electroactive layer comprising multiple electroactive films having different moduli, where the modulus of each film is larger or smaller than adjacent films, and electrodes are disposed on at least one surface to induce vibrations, allowing for sufficient vibration strength across all frequency domains and providing transparent tactile feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a vibration motor such as ERM or LRA is used to provide haptic feedback, then vibration strength can be increased, but the device size must be increased and response speed becomes slow
Solution Approach 1:
The patent replaces traditional mechanical vibration motors (ERM, LRA) with an electroactive polymer-based haptic device that uses electrostatic forces to generate vibrations. This substitution eliminates the need for heavy rotating masses and complex mechanical structures, enabling fast response speeds while maintaining vibration strength through direct electrostatic actuation of the electroactive polymer layer.
Solution Approach 2:
The patent employs a thin-film electroactive polymer layer as the haptic actuator instead of bulky mechanical vibration motors. This thin-film structure enables rapid response due to its low mass and direct coupling with the display panel, while still generating sufficient vibration strength through controlled electrostatic deformation of the polymer film.
2Speed
If electroactive ceramics are used for the haptic device, then response speed improves, but durability against external impact decreases and the material is opaque
Solution Approach 1:
The patent uses electroactive polymer materials that combine the advantages of fast response speed (comparable to ceramics) with superior flexibility, durability, and transparency. The polymer-based composite structure provides impact resistance through its inherent flexibility while maintaining optical transparency for display integration.
3Force
If haptic devices with unique resonance frequency are used, then vibration strength is transmitted in specific frequency domain, but the ability to transmit various textures and tactile feelings is limited
Solution Approach 1:
The patent implements a haptic device with dynamically adjustable vibration characteristics through independent control of multiple electroactive polymer regions. By varying the voltage applied to different regions, the device can modulate vibration frequency and amplitude in real-time, enabling transmission of diverse tactile sensations including different textures, patterns, and vibration modes across multiple frequency domains.
Solution Approach 2:
The patent divides the electroactive polymer layer into multiple independently controllable regions with electrodes disposed on opposite surfaces. This segmentation allows different regions to generate vibrations at different frequencies and amplitudes simultaneously, providing versatile tactile feedback capable of representing various textures and tactile feelings.
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 solution enables excellent response characteristics across all frequency domains, enabling the transmission of various textures and precise tactile sensations to users while maintaining transparency, thus overcoming the limitations of existing haptic devices.
Implementation Method 1
an electroactive layer including a plurality of electroactive films and a plurality of electrodes which is disposed on at least one surface of the electroactive layer
Data Source
AI summary
Provided are a touch sensitive element and a display device. A touch sensitive element according to an exemplary embodiment includes an electroactive layer including a plurality of electroactive films formed of an electroactive polymer; and a plurality of electrodes disposed on at least one surface of the electroactive layer. In this case, the plurality of electroactive films is configured by a first electroactive film, a second electroactive film, and one or more electroactive films between the first electroactive film and the second electroactive film. A modulus of one or more electroactive films is higher or lower than both a modulus of an electroactive film which is in contact with an upper surface and a modulus of an electroactive film which is in contact with a lower surface. The touch sensitive element according to the exemplary embodiment of the present disclosure may implement a sufficient vibration strength in all frequency domains.