Haptic Feedback Device Stiffener Design for Uniform Vibration
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Solution Overview
Problem
Existing haptic return surfaces based on ultrasonic lubrication face challenges in achieving uniform vibration across non-rectangular surfaces, leading to interference and degradation of haptic feedback due to complex geometries and resonance frequency issues.
Innovation Solution
The introduction of one-dimensional stiffener elements on the surface of the support, distributed parallel to each other, creates orthotropy that forces an axial resonance effect in a specific direction, independent of the surface geometry, ensuring uniform and unidirectional vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the support has a non-rectangular geometry (e.g., square, disc, or complex shapes), then the aspect ratio approaches 1 or the geometry becomes complex, but this causes superposition of modes at approximately the same resonant frequency, creating interference and degrading haptic feedback uniformity
Solution Approach 1:
The patent applies local quality by introducing stiffeners at specific locations on the support surface. These stiffeners are strategically positioned to modify the local vibration characteristics and eliminate interference patterns. The stiffeners create zones of different stiffness that guide the vibration energy distribution, ensuring uniform haptic feedback across the entire surface regardless of the overall geometry.
Solution Approach 2:
The patent employs composite materials by combining the original support material with stiffening elements of different material properties. The stiffeners are made from materials with higher stiffness-to-weight ratios, creating a composite structure that maintains the overall geometry flexibility while providing localized rigidity to control vibration modes and eliminate interference.
2Manufacturing precision
If stiffeners are added to the support surface to eliminate interference and achieve uniform vibration, then vibration uniformity is improved, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the support surface into multiple zones with stiffeners placed at specific intervals. Rather than making the entire support rigid, the stiffeners are segmented into discrete elements that provide localized reinforcement. This segmentation approach achieves vibration uniformity while minimizing the added structural complexity and material usage.
Solution Approach 2:
The patent utilizes dimensionality change by adding stiffeners in a specific spatial arrangement on the support surface. The stiffeners are positioned to create a three-dimensional vibration control mechanism that operates in addition to the two-dimensional vibration field. This dimensional approach allows for precise control of vibration modes without significantly increasing 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
This approach enables optimal activation of axial modes across various surface geometries, achieving larger vibrational amplitudes with lower energy expenditure and ensuring a homogeneous haptic return effect.
Implementation Method 1
the support is capable of being set into vibration... capable of setting said support and said layer into vibration at an ultrasonic resonance frequency
Implementation Method 2
a stationary mode is excited which will act as an amplifier by resonance effect
Implementation Method 3
said stiffeners extending in relief relative to it and being capable of limiting the deflection of the plate along an axis perpendicular to the stiffeners
Implementation Method 4
The large displacement amplitudes thus obtained at ultrasonic frequencies lead to the creation of a compressed air cushion under the pad of a user's finger (known as a 'squeeze-film' effect in English terminology). As the finger is pushed back by the surface, the coefficient of friction is reduced
Data Source
Figure 1~3
Figure 4a~5
Figure 6~7
AI summary
The invention relates to a haptic feedback device (1; 10) comprising a support (4) which can be vibrated and of which a first face is coated with at least one layer (2, 3) incorporating a means for detecting the position of a user's finger, the device (1; 10) comprising electromechanical actuators (12) which are aligned along an edge of the support (4) or the layer (2, 3) and which are capable of making the support (4) and the layer (2,3) vibrate at an ultrasonic resonance frequency, characterised in that the support (4) comprises on the second face thereof a set of stiffeners (5) distributed over the whole of said second face and configured to make it more difficult to bend the support (4) along an axis perpendicular to the stiffeners (5), the stiffeners (5) being designed to produce an axial and uniform vibration mode for the support (4), all the antinodes of which are of substantially equal amplitude.