Ultra-thin Inertial Actuator for Haptic Feedback
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Solution Overview
Problem
Conventional miniaturized actuators for mobile applications, such as eccentric rotating mass (ERM) or linear resonant actuator (LRA) coin motors, consume significant power and are limited in application due to size constraints and difficulty in resonance tuning, failing to provide effective haptic responses.
Innovation Solution
An inertial actuator comprising an electroactive polymer (EAP) or electromechanical polymer (EMP) actuator with a substrate and mass elements, which induces vibrations to provide a haptic response, allowing for decoupling of frequency and force over a desired haptic frequency range, and is designed to be thin and flexible for use in handheld devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional miniaturized actuators (ERM or LRA coin motors) are used, then the actuator size is reduced, but power consumption increases significantly
Solution Approach 1:
The patent replaces conventional electromagnetic actuator mechanisms with an electroactive polymer-based inertial actuator. The EAP actuator uses electrochemical or electromechanical effects directly in the polymer material to generate motion, eliminating the need for traditional motor components. This substitution enables miniaturization while reducing power consumption by directly coupling electrical energy to mechanical motion through the polymer's inherent properties rather than through electromagnetic induction in coils.
Solution Approach 2:
The invention employs composite structures combining electroactive polymer layers with electrode layers and inertial mass elements. The multilayer EAP actuator integrates different functional materials (electroactive polymer, conductive electrodes, and inertial mass) into a unified thin-film structure. This composite approach enables the actuator to achieve both miniaturization and energy efficiency by optimizing the interaction between different material layers.
2Volume of moving object
If conventional miniaturized actuators are used, then the actuator size is reduced, but resonance tuning becomes difficult
Solution Approach 1:
The patent implements dynamic resonance tuning by making the inertial mass adjustable. The system can vary the effective mass of the resonator by reconfiguring the EAP actuator's operation or adjusting the inertial elements, allowing the resonant frequency to be tuned dynamically. This dynamic capability enables easy resonance adjustment in miniaturized actuators without complex mechanical tuning mechanisms.
Solution Approach 2:
The invention enables resonance tuning by changing physical parameters of the system, particularly the inertial mass and the stiffness of the EAP actuator. By adjusting these parameters, the resonant frequency can be modified to match desired operating conditions. This parameter-based tuning approach is much simpler than mechanical resonance tuning in conventional actuators.
3Adaptability or versatility
If the EAP actuator is made thin and flexible for handheld devices, then adaptability to display surfaces is improved, but structural strength decreases
Solution Approach 1:
The patent employs thin-film flexible substrates to support the EAP actuator layers. These flexible substrates allow the actuator to conform to curved or flexible display surfaces while maintaining structural integrity. The thin-film construction provides the necessary flexibility for integration into handheld devices with flexible displays, while the distributed structure across multiple layers prevents fracture.
Solution Approach 2:
The multilayer composite structure of the EAP actuator, consisting of alternating electroactive polymer layers and electrode layers on a flexible substrate, provides both flexibility and strength. The distributed reinforcement from multiple thin layers creates a composite structure that is more fracture-resistant than a single thick layer, while maintaining the flexibility needed for display integration.
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 inertial actuator achieves high-definition haptic feedback with low latency and high acceleration, suitable for handheld devices, offering greater fracture resistance and transparency, enabling haptic effects on flexible displays while maintaining mechanical deflection.
Implementation Method 1
the EAP actuator's electromechanical response when an electrical stimulus is applied to the EAP actuator
Implementation Method 2
A discernible haptic response may be provided to a user at a vibration frequency between 100 Hz and 300 Hz
Data Source
AI summary
An inertial actuator includes an electro-active polymer EAP actuator, a substrate, and one or more mass elements. The EAP actuator includes at least one EAP layer located between a pair of driving electrodes. The EAP actuator may include a multilayer stack of alternating EAP layers and electrode layers. The EAP actuator is attached to the substrate (e.g., a flexible polymer substrate), which may be held under tension by attachment points at the periphery of the substrate, at the ends of a beam-type substrate, or the edges of a membrane-type actuator. The EMP actuator induces vibrations in the substrate. One or more mass elements (e.g., metal films) may also be supported by the substrate to enhance the resonator response.