Ultrasonic Haptic Actuator Eliminating Magnetic Interference

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Solution Overview

Problem

Electromagnetic haptic actuators in mobile devices face challenges due to magnetic interference and size constraints, as well as limitations in miniaturization and integration with other device components, particularly with the increasing complexity and smaller form factors of mobile phones.

Innovation Solution

A haptic actuator apparatus utilizing an ultrasonically vibrating motor with a guide structure and springs to generate human-detectable vibrations, which does not produce magnetic interference and can be integrated into smaller volumes without the need for stationary mass components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If electromagnetic ERM or LRA vibration motors are used, then haptic vibration can be generated, but magnetic fields are produced that interfere with other devices in mobile phones

Engineering Contradiction:

Improvehaptic vibration forceVSAvoidmagnetic interference

Core Design Contradiction:

ForceVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the electromagnetic motor system with a piezoelectric ultrasonic motor system. The piezoelectric motor uses piezoelectric ceramics to generate ultrasonic vibrations that drive a friction wheel, which in turn rotates the eccentric mass to produce haptic vibrations. This mechanical substitution eliminates the electromagnetic field generation while maintaining the haptic vibration output, resolving the magnetic interference problem.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operating frequency parameter to ultrasonic frequencies (typically 20-100 kHz) instead of the audible frequencies (50-200 Hz) used by electromagnetic motors. This parameter change enables the use of piezoelectric materials that convert electrical energy directly into mechanical vibrations without generating magnetic fields, thus eliminating magnetic interference while achieving the desired haptic effects.

Inventive Principle:

Principle #35Parameter changes

2Force

If electromagnetic vibration motors are used, then haptic feedback is provided, but the device size increases due to stationary mass components

Engineering Contradiction:

Improvehaptic feedback forceVSAvoidmotor volume

Core Design Contradiction:

ForceVSVolume of moving object

Solution Approach 1:

The patent extracts and eliminates the stationary electromagnetic components (electromagnetic coils, iron cores, and stationary magnets) from the motor structure. By using a piezoelectric ultrasonic motor, the entire motor becomes a moving system where the piezoelectric elements are mounted on a rotating or oscillating component. This extraction of stationary mass significantly reduces the overall motor volume while maintaining haptic feedback capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent transitions from a static electromagnetic motor structure to a dynamic piezoelectric ultrasonic motor structure. The piezoelectric elements are mounted on a moving component that oscillates or rotates at ultrasonic frequencies, creating a fully dynamic system. This dynamic configuration eliminates the need for stationary electromagnetic components, reducing the motor's footprint and enabling better integration into compact mobile devices.

Inventive Principle:

Principle #15Dynamics

3Power

If electromagnetic motors with copper coils and iron cores are used, then torque is generated for rotation, but the conductive materials are not transparent to radio frequencies

Engineering Contradiction:

Improvetorque generationVSAvoidRF signal interference

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The patent employs piezoelectric ceramic materials that combine mechanical, electrical, and acoustic properties in a single material system. These composite piezoelectric structures generate mechanical vibrations and torque without requiring separate copper coils and iron cores. The piezoelectric ceramics are inherently non-conductive and RF-transparent, eliminating the radio frequency interference problem while maintaining the necessary mechanical power output for haptic feedback.

Inventive Principle:

Principle #40Composite materials

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 solution provides a haptic actuator that generates more force in a smaller volume than previous devices, eliminating magnetic interference and enabling better integration with other mobile device components, particularly in highly miniaturized systems.

Implementation Method 1

A haptic actuator apparatus utilizes an ultrasonically vibrating motor

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

The spring delimits the path and generates human-detectable vibrations in response to an impact with the ultrasonically vibrating motor

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS8797152B2Haptic actuator apparatuses and methods thereof

Publication Date: 2014.08.05 NEW SCALE TECH

AI summary

A haptic actuator apparatus and a method of making the same include an ultrasonically vibrating motor and its housing. The housing includes a guide structure coupled to the ultrasonically vibrating motor and at least one spring. The guide structure defines at least one path of motion of the ultrasonically vibrating motor. The at least one spring delimits the at least one path and generates human-detectable vibrations in response to an impact with the ultrasonically vibrating motor.