Electrostatic Touchscreen Actuator with Parallel Guide
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electrostatic parallel-plate actuators in touchscreens experience uncontrolled movement due to a shift in force balance as the deflection stroke increases, leading to tilting of the touch surface and impaired haptic feedback, especially with off-center forces.
Innovation Solution
The use of a three-electrode plate configuration with a parallel guide ensures a larger deflection range while maintaining force balance, and the integration of a parallelogram guide and restoring elements prevents tilting, along with air ducts to reduce braking effects and a flexible sealing element for relative movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the deflection stroke of the electrostatic parallel-plate actuator is increased, then the haptic feedback range is improved, but the force balance shifts causing uncontrolled movement and tilting
Solution Approach 1:
The single electrode plate is divided into three separate electrode plates arranged in series. Each electrode plate can be independently controlled and deflected, allowing the total deflection stroke to be distributed across multiple segments. This segmentation enables each segment to maintain its own force balance while achieving a larger overall deflection range when combined.
Solution Approach 2:
The solution transitions from a single-plane deflection system to a multi-layer stacked configuration. By arranging electrode plates in three dimensions (stacked vertically), the system achieves extended deflection stroke in the vertical direction while maintaining stability in the horizontal plane through the parallel guide constraints.
2Length of moving object
If the deflection stroke is increased, then the haptic feedback effect is improved, but tilting of the contact surface occurs impairing haptic feedback
Solution Approach 1:
A parallel guide is introduced as an intermediary mechanism between the electrode plates and the housing. This parallel guide acts as a constraint that mediates the movement of the electrode plates, ensuring they deflect in a controlled manner without tilting. The parallel guide translates the electrostatic force into pure translational movement, maintaining the parallelism of the contact surface throughout the extended deflection stroke.
3Device complexity
If a single electrode plate configuration is used, then the device structure is simple, but the deflection range is limited
Solution Approach 1:
The electrode plate is segmented into three separate plates stacked in series. Each plate contributes to the total deflection stroke, effectively tripling the potential deflection range compared to a single plate configuration. The segmented structure allows each plate to be controlled independently while working together to achieve the extended overall movement.
Solution Approach 2:
The three electrode plates are arranged in a nested, stacked configuration where each plate is positioned within the magnetic field region of the others. This nested arrangement maximizes the use of available space and allows the magnetic fields to interact constructively, achieving extended deflection stroke without proportionally increasing the overall device footprint.
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 configuration allows for controlled deflection and return characteristics over a wider range without excessive deviations, ensuring precise parallel movement and improved haptic feedback by maintaining force balance and reducing braking effects.
Implementation Method 1
If a voltage is now applied to the electrode plates, electrostatic forces arise which act in the sense of a repulsion or attraction of the electrode plates and cause a corresponding deflection of the movably held electrode plate.
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to an input element, for example touchscreen, for electronic apparatuses, having a contact surface which can be moved in a translatory manner and interacts with an actuator, wherein the actuator is in the form of an electrostatic parallel-plate actuator the electrode plates of which are held at a variable normal distance in relation to one another, wherein the electrode plate which interacts with the contact surface can be deflected against the force of a restoring element, for example spring element, the electrostatic parallel-plate actuator has at least three electrode plates which are arranged one above the other and which are each held such that they can be deflected against the force of a restoring element relative to the electrode plate situated immediately therebeneath, that is to say the user can in this way receive, for example, tactile feedback when touching the touchscreen. Furthermore, parallel guidance for the electrode plate which interacts with the contact surface is provided.