Piezoelectric Drive Device Stacked Vibration Segmentation

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Solution Overview

Problem

Piezoelectric drive devices face a challenge in increasing holding force without excessively increasing drive force, leading to larger device sizes and higher costs due to the need for multiple drive portions.

Innovation Solution

A piezoelectric drive device configuration featuring a vibration module with a first and second vibration portion stacked in a specific direction, where the first vibration portion performs lateral vibration and the second performs longitudinal vibration, allowing for composite vibration to enhance holding force without excessive drive force, using a control unit to manage these vibrations and optimize the pressing force against the driven rotor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If the number of piezoelectric drive portions is increased to increase holding force, then the holding force is improved, but the drive force becomes excessively large and the device size increases

Engineering Contradiction:
Improveholding forceVSAvoiddrive force
Core Design Contradiction:
ForceVSPower

Solution Approach 1:

The piezoelectric drive portions are segmented into first and second types with distinct functions. The first piezoelectric drive portions generate lateral vibration for driving force, while the second piezoelectric drive portions generate longitudinal vibration for holding force. This functional segmentation allows independent optimization of drive and holding forces without requiring proportional increases in both.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the piezoelectric drive device are assigned different local qualities: the first piezoelectric drive portions are configured to produce lateral vibration with specific amplitude and frequency characteristics for driving, while the second piezoelectric drive portions are configured to produce longitudinal vibration with different characteristics for holding. This local differentiation enables precise control over the balance between drive force and holding force.

Inventive Principle:
Principle #3Local quality

2Force

If the number of piezoelectric drive portions is increased to increase holding force, then the holding force is improved, but the device size is increased

Engineering Contradiction:
Improveholding forceVSAvoiddevice size
Core Design Contradiction:
ForceVSVolume of moving object

Solution Approach 1:

The first and second piezoelectric drive portions are merged into a single integrated piezoelectric drive device structure. Both types of drive portions operate simultaneously within the same device footprint, generating composite vibration that provides both driving and holding functions. This merging eliminates the need for separate dedicated holding mechanisms, thereby increasing holding force without proportionally increasing device size.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The piezoelectric drive device achieves multi-functionality by enabling the same device structure to provide both driving function (through lateral vibration from first piezoelectric drive portions) and holding function (through longitudinal vibration from second piezoelectric drive portions). This universal design allows a single device to perform multiple functions that would traditionally require separate components, thereby improving holding force without increasing device size.

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

3Force

If the number of piezoelectric drive portions is increased to increase holding force, then the holding force is improved, but the device complexity is increased

Engineering Contradiction:
Improveholding forceVSAvoiddevice complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The piezoelectric drive portions self-regulate their vibration characteristics based on their inherent properties and the applied drive signal. The first piezoelectric drive portions automatically generate lateral vibration at appropriate amplitudes for driving, while the second piezoelectric drive portions generate longitudinal vibration for holding. This self-service mechanism reduces the need for complex external control systems and feedback mechanisms, thereby increasing holding force without proportionally increasing device complexity.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The device utilizes parameter changes in the vibration characteristics (amplitude, frequency, direction) of the piezoelectric drive portions to achieve different functions. By controlling the drive signal parameters, the first piezoelectric drive portions produce lateral vibration for driving while the second produce longitudinal vibration for holding. This parameter-based control allows flexible adjustment of drive and holding forces without requiring complex mechanical structures, thereby improving holding force while maintaining manageable device complexity.

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

This configuration effectively increases the holding force of the driven rotor while maintaining a balanced drive force, enabling a more compact and cost-effective design by utilizing a combination of lateral and longitudinal vibrations to enhance the pressing force and reduce the size and cost of the device.

Implementation Method 1

the control unit is configured to cause the first vibration portion to perform lateral vibration to vibrate in a third direction intersecting the first direction and the second direction

Methodology Applied
Scientific EffectLateral vibration: Vibration

Implementation Method 2

the control unit is configured to cause the second vibration portion to perform longitudinal vibration to vibrate in the first direction

Methodology Applied
Scientific EffectLongitudinal vibration: Vibration

Implementation Method 3

a piezoelectric drive device includes a piezoelectric vibration module including a vibration portion and a transmission portion

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentEP3396726B1Piezoelectric drive device and drive method of piezoelectric drive device
Publication Date: 2021.06.30 SEIKO EPSON CORP
  • EP3396726B1 patent drawingFigure 1
  • EP3396726B1 patent drawingFigure 2
  • EP3396726B1 patent drawingFigure 3

AI summary

A piezoelectric drive device includes a piezoelectric vibration module including a vibration portion and a transmission portion which abuts a driven portion and transmits vibration of the vibration portion to the driven portion and a control unit, and the vibration portion includes a first vibration portion and a second vibration portion disposed to be stacked in a second direction intersecting a first direction which is a direction in which the vibration portion is aligned with the driven portion, and the control unit causes the first vibration portion to vibrate in a third direction intersecting the first direction and the second direction and causes the second vibration portion to vibrate in the first direction.