Piezoelectric Power Generation Unit Deformation Control

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Solution Overview

Problem

Existing power generation units using piezoelectric materials face challenges in miniaturization due to excessive deformation of deforming members, which can lead to collisions and damage, requiring additional components like elastic bodies for impact absorption.

Innovation Solution

A power generation unit incorporating a deforming member with a piezoelectric device, a displacement sensor, an inductor, and a switch controlled by a switch control section to set the electrodes to a shorted state when deformation exceeds a predetermined level, inhibiting excessive deformation and eliminating the need for impact absorption components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an elastic body is provided to absorb impact when the cantilever collides with the housing wall, then the reliability is improved, but the device complexity and volume increase

Engineering Contradiction:

Improveprotection against cantilever collision damageVSAvoidadditional elastic body component

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical impact absorption system (elastic body) with an electrical control system. The piezoelectric device generates electrical signals in response to cantilever deformation, which are then processed by a control circuit that applies reverse polarity voltage to limit further deformation. This substitutes mechanical protection with electrical-field-based control, eliminating the need for additional mechanical components like elastic bodies.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the electrical parameters (voltage polarity and magnitude) of the piezoelectric device to control the cantilever's mechanical behavior. By switching the voltage polarity when excessive deformation is detected, the system actively adjusts the piezoelectric effect to limit the cantilever's swing amplitude, thereby preventing collision without requiring mechanical buffer components.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If the cantilever is allowed to swing freely to maximize power generation, then the energy output is improved, but the risk of collision and damage increases

Engineering Contradiction:

Improvepower generation efficiencyVSAvoidcollision risk to cantilever

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent implements a feedback control mechanism where the piezoelectric device continuously monitors the cantilever's deformation state and generates electrical signals proportional to the deformation. The control circuit processes this feedback information and adjusts the voltage applied to the piezoelectric device in real-time, creating a closed-loop system that maximizes power generation while preventing excessive swing and collision.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system applies preliminary anti-action by detecting when the cantilever approaches its safe swing limit and preemptively applying reverse polarity voltage to counteract the deformation before collision occurs. This preventive control allows the cantilever to utilize nearly its full safe range of motion for power generation while avoiding the harmful collision state.

Inventive Principle:

Principle #9Preliminary anti-action

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 the miniaturization of the power generation unit while efficiently generating higher voltages without additional step-up circuits, by accurately controlling the deformation of the piezoelectric device and storing charges effectively.

Implementation Method 1

When a piezoelectric material such as lead zirconium titanate (PZT), quartz crystal (SiO2), or zinc oxide (ZnO) is deformed, electrical polarization is induced inside the material, and positive and negative charges appear on the surface. Such a phenomenon is called a so-called piezoelectric effect.

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

an inductor electrically connected to the piezoelectric device

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS8941289B2Power generation unit, electronic apparatus, transportation device, and method of controlling power generation unit

Publication Date: 2015.01.27 SEIKO EPSON CORP

AI summary

A power generation unit includes: a deforming member adapted to deform while switching a deformation direction; a piezoelectric device provided to the deforming member, and having a pair of electrodes; a displacement sensor adapted to detect a deformation amount of the deforming member, and then output deformation amount information as information related to the deformation amount; an inductor electrically connected to the piezoelectric device; a switch disposed between the piezoelectric device and the inductor; and a switch control section adapted to control the switch so as to set the pair of electrodes to a shorted state for a predetermined period of time when the deformation amount exceeds a predetermined level.