Transformer-Coupled Vibration Actuator for Phase-Uniform Drive

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Solution Overview

Problem

Existing vibration actuators using multiple vibrators connected in series or parallel suffer from differences in vibration phase and amplitude, leading to reduced driving efficiency due to sliding losses and high voltage requirements.

Innovation Solution

The vibrators are connected in parallel to secondary coils of transformers, with primary coils in series, allowing for uniform vibration amplitudes and phases without increasing the applied voltage, using a low-voltage drive circuit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If vibrators are connected in parallel to a common drive circuit, then the circuit structure is simplified, but differences in vibration amplitude and phase increase due to variations in resonance frequency and load

Engineering Contradiction:
Improvecircuit structureVSAvoidvibration uniformity
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent divides the drive circuit into separate individual drive circuits for each vibrator instead of using a common drive circuit. This segmentation allows each vibrator to be driven independently with optimized parameters, reducing the negative impact of resonance frequency and load variations on vibration uniformity while maintaining circuit simplicity through modular design.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by allowing each vibrator to have its own customized drive circuit parameters (such as resonance frequency matching and load compensation) tailored to its specific characteristics. This enables each vibrator to operate at optimal conditions, ensuring uniform vibration amplitude and phase across all vibrators despite their individual differences.

Inventive Principle:
Principle #3Local quality

2Reliability

If piezoelectric devices are connected in series, then differences in electric current become small, but voltage rises to high voltage level

Engineering Contradiction:
Improvecurrent uniformityVSAvoidvoltage level
Core Design Contradiction:
ReliabilityVSStress or pressure

Solution Approach 1:

The patent employs dynamic parameter adjustment in individual drive circuits to maintain current uniformity across series-connected piezoelectric devices without requiring high voltage. Each drive circuit dynamically adapts its output parameters based on the specific vibrator's characteristics, enabling the system to operate at lower voltage levels while ensuring uniform current distribution.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the control parameters of each individual drive circuit to compensate for variations in piezoelectric devices. By adjusting parameters such as drive frequency, voltage amplitude, and phase individually for each device, the system achieves current uniformity without needing to raise the overall voltage to high levels.

Inventive Principle:
Principle #35Parameter changes

3Stress or pressure

If piezoelectric devices are connected in parallel, then circuit voltage remains low, but differences in vibration amplitude become large due to resonance frequency variations

Engineering Contradiction:
Improvevoltage levelVSAvoidvibration amplitude uniformity
Core Design Contradiction:
Stress or pressureVSReliability

Solution Approach 1:

The patent segments the drive system into independent drive circuits for each piezoelectric device, allowing low-voltage parallel operation while maintaining vibration amplitude uniformity through individual parameter optimization. Each segmented drive circuit can be tuned to its specific device characteristics, eliminating the amplitude variations that would otherwise occur in parallel connections.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements feedback mechanisms in individual drive circuits to monitor and adjust vibration parameters in real-time. This feedback control ensures that vibration amplitude remains uniform across all parallel-connected piezoelectric devices by continuously compensating for resonance frequency variations and load differences.

Inventive Principle:
Principle #23Feedback

4Device complexity

If multiple vibrators are driven by a common drive circuit, then circuit structure is reduced, but sliding loss increases due to vibration phase differences

Engineering Contradiction:
Improvecircuit structureVSAvoidsliding loss
Core Design Contradiction:
Device complexityVSLoss of energy

Solution Approach 1:

The patent segments the drive system into individual drive circuits for each vibrator, eliminating vibration phase differences caused by common drive circuit limitations. This segmentation reduces sliding loss by ensuring synchronized vibration across all contact members while maintaining acceptable circuit complexity through modular architecture.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses feedback control in individual drive circuits to synchronize vibration phases across multiple vibrators. By monitoring and adjusting phase parameters individually, the system minimizes sliding loss between contact members while keeping the overall circuit structure manageable through distributed control.

Inventive Principle:
Principle #23Feedback

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 ensures efficient transfer of thrust to the contact member with reduced voltage requirements, maintaining consistent vibration phases and amplitudes, thereby enhancing driving efficiency and allowing for continuous operation even with partial failures.

Implementation Method 1

a first vibrator (43) having a first piezoelectric member (47)

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

a first friction member (24) and configured to vibrate the first friction member (24) in a contact portion (24a) to linearly move the contact member (22)

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3731401B1Vibration actuator and driving device for vibration actuator
Publication Date: 2025.10.15 CANON KK
  • EP3731401B1 patent drawingFigure 1A~1B
  • EP3731401B1 patent drawingFigure 2A~2B
  • EP3731401B1 patent drawingFigure 3A~3B

AI summary

A vibration actuator that is capable of reducing differences in vibration phase and vibration amplitude without rising a voltage of a drive circuit when driving a contact member using a plurality of vibrators connected in series. A vibration actuator includes a vibrator device and a contact member that moves relative to the vibrator device. The vibrator device includes transformers (5, 6, 7) of which primary coils are connected in series, and vibrators (1, 2, 3) that are respectively connected in parallel to secondary coils of the transformers.