Multilayer Capacitor Noise Reduction via Opposing Electrode Sections

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Solution Overview

Problem

Multilayer capacitors using ceramics with high dielectric constants experience acoustic noise due to mechanical distortion when a DC voltage with an AC component is applied, as existing solutions like Japanese Unexamined Patent Application Publication No. 2013-258278 do not fully mitigate this issue.

Innovation Solution

A multilayer capacitor design with first and second capacitor sections connected in opposite phases, where the first capacitor section is connected to voltage smoothing and the second section reduces potential difference, with specific electrode configurations and orientations to cancel out expansion and contraction, reducing noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a DC voltage with AC component is applied to a multilayer capacitor using high dielectric constant ceramics, then voltage smoothing function is achieved, but acoustic noise occurs due to mechanical distortion

Engineering Contradiction:

Improvevoltage smoothing functionVSAvoidacoustic noise

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The multilayer capacitor is divided into multiple capacitor sections (first, second, third sections) with different electrode area ratios. Each section has inner electrodes with specific area relationships (first section: 1:2 ratio, second section: 1:1 ratio, third section: 2:1 ratio) to create different expansion/contraction characteristics that collectively reduce acoustic noise while maintaining voltage smoothing function.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different capacitor sections are designed with locally differentiated electrode area ratios to create specific mechanical response characteristics. The first capacitor section has a 1:2 area ratio, the second has 1:1, and the third has 2:1, allowing each local region to contribute differently to noise reduction while collectively achieving the overall function.

Inventive Principle:

Principle #3Local quality

2Object-generated harmful factors

If capacitor sections are arranged to cancel expansion and contraction, then acoustic noise is reduced, but device complexity increases

Engineering Contradiction:

Improveacoustic noise reductionVSAvoidmultilayer structure complexity

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

Multiple capacitor sections with different electrode area ratios are combined within a single multilayer body structure. The first, second, and third capacitor sections are integrated together, sharing common outer electrodes and dielectric layers, to achieve noise reduction through their combined mechanical response without requiring separate components.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The multilayer capacitor structure serves multiple functions simultaneously: voltage smoothing through capacitive action, acoustic noise reduction through differential expansion/contraction cancellation, and mechanical stability through the balanced electrode area ratios. Each capacitor section contributes to both electrical and mechanical functions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Effectively reduces or prevents acoustic noise by canceling out expansion and contraction in the capacitor sections, minimizing distortion and noise transmission to circuit boards even under DC voltage with AC components.

Implementation Method 1

Ceramics having a high dielectric constant have piezoelectricity and electrostriction. Accordingly, in a multilayer capacitor using ceramics having a high dielectric constant, vibration occurs due to a mechanical distortion if a direct current (DC) voltage on which an alternating current (AC) voltage or an AC component is superposed is applied to the multilayer capacitor.

Methodology Applied

Scientific EffectPiezoelectricity: Piezoelectric Effect

Implementation Method 2

Methodology Applied

Scientific EffectElectrostriction: Electrostriction

Data Source

PatentUS9633786B2Multilayer capacitor and usage method therefor

Publication Date: 2017.04.25 MURATA MFG CO LTD

AI summary

A multilayer capacitor includes a multilayer body including a dielectric layer, first through third inner electrodes, and first and second capacitor sections, and first through third outer electrodes on surfaces of the multilayer body. The first capacitor section is electrically connected between the first and second outer electrodes. The second capacitor section is electrically connected between the second and third outer electrodes. The first, second, and third inner electrodes are connected to the first, second, and third outer electrodes, respectively. The first and third inner electrodes oppose each other with the dielectric layer therebetween, thus defining the first capacitor section. The second and third inner electrodes oppose each other with the dielectric layer therebetween, thus defining the second capacitor section.