Reversible Actuator Radial Segmentation for Haptic Feedback

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Solution Overview

Problem

Current haptic actuators in touch display interfaces, such as smartphones and touchpads, are limited by their bulky size and lack of realistic feedback, using inertia-type actuators that provide only whole device vibration and complex mechanical designs.

Innovation Solution

A reversible actuator with an electroactive layer on a substrate featuring radial slots and segments, which changes shape in response to electrical signals, allowing for independent or collective electrical coupling to a control circuit for precise haptic feedback, and is fabricated using laser cutting and hot pressing techniques.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If inertia-type actuators (ERM, LRA) are used for haptic feedback, then the device can provide vibration feedback, but the actuator becomes bulky and provides only whole device vibration without realistic feedback

Engineering Contradiction:
Improvehaptic feedback realismVSAvoidactuator size
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The actuator substrate is divided into multiple segments by radial slots extending from the center. Each segment can be independently actuated by the electroactive layer, enabling localized haptic feedback rather than whole-device vibration. This segmentation allows for more compact design while providing realistic tactile sensations at specific contact points.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent replaces traditional inertia-type mechanical actuators (ERM, LRA) with an electroactive layer that directly converts electrical energy to mechanical deformation. This substitution eliminates the need for heavy rotating or resonating mechanical components, significantly reducing actuator size while providing precise, localized haptic feedback through direct material actuation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If traditional haptic actuators are used, then the device can provide vibration feedback, but the mechanical design becomes complex

Engineering Contradiction:
Improvehaptic feedback capabilityVSAvoidmechanical design complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical actuator mechanisms with a straightforward electroactive layer system. The electroactive layer, when voltage is applied, directly changes shape to produce haptic feedback, eliminating the need for complex mechanical linkages, gears, or resonating components found in traditional actuators.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The electroactive layer serves multiple functions simultaneously: it acts as both the actuating element and the structural component of the actuator. The radial slots and segment design allow this single layer to provide both the mechanical structure and the actuation mechanism, simplifying the overall design while maintaining haptic feedback capability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Manufacturing precision

If radial slots with enlarged apertures are created in the actuator substrate, then the actuation precision and response time are improved, but the manufacturing process becomes more complex

Engineering Contradiction:
Improveactuation precisionVSAvoidmanufacturing process simplicity
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The radial slots divide the actuator substrate into segments that can be independently controlled. The enlarged apertures at the ends of these slots allow for precise actuation of each segment by the electroactive layer, improving overall actuation precision while maintaining a relatively simple manufacturing process through laser cutting.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent optimizes the geometry of the radial slots, particularly the enlarged aperture dimensions and positions, to achieve optimal actuation precision and response time. By carefully selecting and adjusting these geometric parameters during the laser cutting process, high precision actuation is achieved while keeping the manufacturing process straightforward.

Inventive Principle:
Principle #35Parameter changes

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 enables improved haptic feedback with increased precision and realism, providing larger actuation forces and faster response times, enhancing user experience through customizable and efficient haptic interactions.

Implementation Method 1

The electroactive layer is configured to change shape in response to an electrical signal applied to the first electrode and the second electrode

Methodology Applied
Scientific EffectElectroactive layer effect: Electroactive Polymer

Implementation Method 2

laser cutting a plurality of radial slots into the actuator substrate

Methodology Applied
Scientific EffectLaser cutting: Laser Ablation

Implementation Method 3

shaping, for example hot pressing, a portion of the actuator substrate into a protruded portion

Methodology Applied
Scientific EffectHot pressing: Hot Isostatic Pressing

Data Source

PatentEP3620895B1Reversible actuator, method for producing and device using the same
Publication Date: 2022.07.13 ROBERT BOSCH GMBH
  • EP3620895B1 patent drawingFigure 1
  • EP3620895B1 patent drawingFigure 2
  • EP3620895B1 patent drawingFigure 3

AI summary

A reversible actuator including an actuator substrate including an electroactive layer in contact with first and second electrodes, the electroactive layer being configured to change shape in response to an electrical signal applied to the electrodes, wherein the actuator substrate comprises a center and a plurality of radial slots radially extending from the center together with enlarged apertures and protruded portion, the portions between adjacent slots of the plurality of radial slots defining a plurality of segments. A method for producing a reversible actuator, comprising providing the actuator substrate comprising the electroactive layer; laser cutting the plurality of radial slots into the actuator substrate; hot pressing a portion of the actuator substrate into the protruded portion. An interface comprising reversible actuators provided on a common actuator substrate, and electrically coupleable to a control circuit so that electrical signal may be applied independently to each of the plurality of reversible actuators.