Piezoelectric Haptic Actuator With Reinforcing Elements for Screen Deflection
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Solution Overview
Problem
Existing devices for generating haptic feedback on touch-sensitive screens are complex, inefficient, and costly, with a need for a simpler, space-saving, and cost-effective solution that can provide the required deflection for user feedback, particularly in the automotive sector where users cannot constantly look at the screen.
Innovation Solution
A device comprising a piezoelectric actuator with multiple layers and internal electrodes, arranged between reinforcing elements that increase rigidity and stroke, forming a compact and efficient oscillating mass-spring system, where the actuator expands transversely to the polarization direction when an electrical voltage is applied, generating haptic feedback by moving the screen parallel to its surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing devices for generating haptic feedback are used, then haptic feedback can be provided, but the device complexity is high and manufacturing costs are high
Solution Approach 1:
The piezoelectric actuator is divided into multiple thin piezoelectric layers (at least three) stacked in series, with internal electrodes arranged between them. This segmentation allows the actuator to achieve the required stroke and stiffness through cumulative displacement of individual layers, reducing the need for a single complex high-performance component.
Solution Approach 2:
The piezoelectric layers are stacked one on top of another with internal electrodes nested between them, forming a compact multi-layer structure. This nested arrangement maximizes the displacement output within a limited space while maintaining structural integrity and reducing overall device complexity.
2Reliability
If existing devices for generating haptic feedback are used, then haptic feedback can be provided, but the translation efficiency is low
Solution Approach 1:
The piezoelectric layers are designed to expand dynamically in response to applied voltage, with the expansion occurring perpendicular to the polarization direction (d31 effect). The reinforcing elements are designed to deform elastically, converting the small lateral expansion of the piezoelectric actuator into a larger screen offset through mechanical leverage.
Solution Approach 2:
The patent optimizes the stack height to be less than or equal to 3 mm and adjusts the number of piezoelectric layers and their thickness to achieve the desired stroke and stiffness characteristics. The reinforcing elements are designed with specific geometries to amplify the displacement output, improving the translation efficiency from electrical input to mechanical screen movement.
3Force
If a piezoelectric actuator with multiple stacked layers is used to increase stiffness, then the screen offset capability improves, but the stack height increases
Solution Approach 1:
Instead of uniformly increasing stack height to achieve stiffness, the patent uses localized reinforcing elements positioned strategically around the piezoelectric actuator. These reinforcing elements provide the necessary structural support and stiffness amplification at specific locations without requiring a uniform increase in the overall stack height.
Solution Approach 2:
The patent transitions from solving the stiffness problem in the vertical dimension (increasing stack height) to solving it in the lateral dimension through reinforcing elements. The reinforcing elements convert the small lateral expansion of the compact piezoelectric actuator into a larger screen offset, achieving the required stiffness and displacement without increasing the stack height beyond 3 mm.
4Length of moving object
If the piezoelectric actuator expands perpendicular to the polarization direction (d31 effect), then the stroke is increased, but the expansion direction becomes perpendicular to the stacking direction
Solution Approach 1:
The reinforcing elements are designed to deform elastically in response to the lateral expansion of the piezoelectric actuator. When voltage is applied, the piezoelectric actuator expands perpendicular to its stacking direction, and the reinforcing elements convert this lateral expansion into a useful screen offset through their elastic deformation and geometric configuration.
Solution Approach 2:
The reinforcing elements act as intermediaries that convert the lateral expansion of the piezoelectric actuator (perpendicular to stacking direction) into the desired screen offset. They mediate between the actuator's natural expansion direction and the required motion direction, making the d31 effect useful for screen displacement.
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 provides effective haptic feedback with reduced manufacturing costs and space requirements, achieving the necessary deflection duration and stiffness for user feedback, enhancing usability in automotive applications.
Implementation Method 1
the piezoelectric actuator expands when an electrical voltage is applied perpendicular to the polarization direction of the piezoelectric layers and to the electric field (d31 effect)
Data Source
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AI summary
The invention relates to a device (10) for producing haptic feedback, comprising - at least one piezoelectric actuator (11) having a plurality of piezoelectric layers (22), - a first reinforcing element (13a) and a second reinforcing element (13b), wherein the piezoelectric actuator (11) is arranged between the reinforcing elements (13a, 13b), wherein the piezoelectric actuator (11) is designed and arranged so as to change its dimensions when an electrical voltage is applied in a first direction (R1) and wherein the reinforcing elements (13a, 13b) are designed and arranged so as to be deformed as a result of the change in the dimensions of the piezoelectric actuator (11) in such a way that a sub-region (17a, 17b) of the respective reinforcing elements (13a, 13b) is moved relative to the piezoelectric actuator (11) in a second direction (R2) which is perpendicular to the first direction (R1). The invention further relates to an electronic device which comprises the device and to the use of the device.