Vibrating Tactile Interface Using Standing Lamb Waves
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Solution Overview
Problem
Existing tactile interfaces using Rayleigh surface waves are fragile, generate low vibration amplitudes, and are bulky, while those using Lamb waves are limited by small exploratory surfaces and are one-dimensional.
Innovation Solution
A tactile interface that generates standing Lamb waves in a piezoelectric plate with a matrix of ceramics, allowing for a robust, compact, and two-dimensional surface with sufficient peak-to-peak amplitude for a 'squeeze film' effect, enabling direct digital contact without finger heating and with a larger exploratory surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If Rayleigh surface wave transducers are used, then the substrate can be thin and flexible, but the substrate becomes very fragile and heats up quickly
Solution Approach 1:
The patent changes the wave type parameter from Rayleigh surface waves to Lamb waves, which fundamentally alters the vibration characteristics and thermal properties of the substrate, enabling robust operation without fragility and heating issues
Solution Approach 2:
The patent uses a rigid support plate that copies or replicates the vibrating surface of the thin piezoelectric substrate, allowing the thin substrate to operate without direct mechanical stress or heat exposure, thus maintaining structural integrity
2Volume of moving object
If Rayleigh surface wave transducers are used, then the device can be compact, but the vibration amplitudes obtained are extremely low
Solution Approach 1:
The patent introduces a rigid support plate as an intermediary between the thin piezoelectric substrate and the user's finger. This mediator amplifies the vibration amplitude from nanometer scale to micrometer scale while keeping the device compact, as the support plate's rigidity allows for larger vibration transmission
3Force
If Lamb wave transducers are used, then vibration amplitudes are markedly greater, but the exploratory surface is small and limited to one dimension
Solution Approach 1:
The patent transitions from one-dimensional Lamb wave propagation to two-dimensional vibration patterns by using a plate structure with multiple vibration modes (symmetrical and antisymmetric modes), enabling exploration in multiple directions across a larger surface area
4Object-affected harmful factors
If an intermediate pad is used with Rayleigh waves, then finger heating is prevented and vibrations are amplified, but the device becomes more complex
Solution Approach 1:
The patent merges the functions of the thin piezoelectric substrate, rigid support plate, and thermal insulation into a single integrated Lamb wave transducer structure, eliminating the need for separate intermediate pads and reducing overall device 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
The interface provides a mechanically robust, compact, and two-dimensional tactile experience with a significant 'squeeze film' effect, allowing for the simulation of fine textures and roughness in multiple directions, overcoming the limitations of previous technologies.
Implementation Method 1
a piezoelectric layer (21), which is fixed to the substrate (20) and generating, when supplied with an electrical signal, mechanical vibrations
Implementation Method 2
making it possible to obtain a 'squeeze film' effect. This interface makes it possible to reproduce very fine textures or roughness by touch, by modulating the 'squeeze film' effect
Data Source
Figure 1~2
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AI summary
The tactile interface (1) comprises: - a vibrating structure (2) including a plate (20), one face (20a) of which forms the vibrating contact surface of the interface intended to be in contact with a user's finger, and a piezoelectric layer (21) fixed to the other face of said plate, and - power supply means connected to the piezoelectric layer (21). The plate (20), the piezoelectric layer (21), and the power supply means are adapted to generate, within the vibrating structure (2), stationary Lamb waves having a propagation direction along at least one straight axis. The tactile interface makes it possible to reproduce very fine textures or roughnesses by touch, by modifying the tactile sensation of touching the contact surface (20a), and by modulating the "squeeze film" effect.