Liquid Dispenser Head Resin Layer Thickness Control

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Solution Overview

Problem

The manufacturing of liquid dispenser heads with high nozzle density and precision is challenged by variations in thickness of vibration plates due to etchant erosion of adhesive layers and thermal expansion mismatches between metal and resin materials, leading to unacceptable variations in vibration performance and droplet discharge quality.

Innovation Solution

A liquid dispenser head is manufactured with a vibration member comprising a metal member and a resin layer directly formed on the metal, where the resin layer has a higher coefficient of linear expansion than the metal, allowing for controlled thickness and reduced wrinkle formation, thereby maintaining consistent vibration performance across nozzles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If an adhesive agent is used to bond polymer film to metal plate, then bonding strength is improved, but thickness variation increases due to etchant erosion

Engineering Contradiction:

Improvebonding strengthVSAvoidthickness variation

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The patent removes the adhesive agent from the bonding structure between the metal plate and polymer film. By extracting this intermediate layer, the patent eliminates the source of thickness variation caused by etchant erosion while maintaining bonding strength through direct contact or alternative bonding methods that do not rely on adhesive layers susceptible to chemical erosion.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the adhesive agent intermediary layer with a direct bonding interface or an intermediary layer that is resistant to etchant erosion. This substitution maintains the necessary bonding function while preventing the thickness variation problem that arises from adhesive erosion during the etching process.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If nozzle density is increased, then image quality is improved, but vibration performance varies due to thickness variation

Engineering Contradiction:

Improveimage qualityVSAvoidvibration performance consistency

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent employs piezoelectric elements that utilize electro-mechanical coupling to generate precise vibrations. The piezoelectric material's inherent property of converting electrical signals to mechanical vibrations allows for controlled and consistent vibration performance across all nozzles, eliminating the need for mechanical vibration plates that are susceptible to thickness variation and ensuring uniform droplet discharge for high image quality.

Inventive Principle:

Principle #29Pneumatics and hydraulics

Solution Approach 2:

The patent changes the material parameter of the vibration generating element from mechanical (metal plate with polymer film) to piezoelectric material. This parameter change enables precise control of vibration frequency and amplitude through electrical signals, ensuring consistent vibration performance across all nozzles regardless of geometric variations, thereby maintaining high image quality while improving reliability.

Inventive Principle:

Principle #35Parameter changes

3Shape

If resin layer has higher coefficient of linear expansion than metal, then wrinkle formation is reduced, but thermal expansion mismatch increases

Engineering Contradiction:

Improvewrinkle formationVSAvoidthermal expansion mismatch

Core Design Contradiction:

ShapeVSStability of the object's composition

Solution Approach 1:

The patent uses a composite structure combining metal plate and piezoelectric material with complementary thermal expansion properties. The piezoelectric material's thermal expansion coefficient is selected to be between that of the metal substrate and the polymer film, creating a composite structure that balances thermal stress management with wrinkle prevention. This composite approach allows the resin layer to have higher thermal expansion than the metal while minimizing overall thermal mismatch through the intermediate piezoelectric layer.

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 approach ensures stable droplet discharge performance by effectively transmitting displacement energy from the piezoelectric element to the liquid chamber, reducing variations and enhancing the reliability of the liquid dispenser head.

Implementation Method 1

a piezoelectric element is used

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

the resin layer has a coefficient of linear expansion greater than a coefficient of linear expansion of the metal member

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS8042917B2Liquid dispenser head, liquid dispensing unit using same, image forming apparatus using same, and method of manufacturing liquid dispenser head

Publication Date: 2011.10.25 RICOH CO LTD

AI summary

A liquid dispenser head includes a plurality of nozzles, a plurality of liquid chambers, and a plurality of vibration members. The nozzle is used to discharge liquid. The liquid chamber communicates with the nozzle. The vibration member has a vibration portion, which is used as a deformable wall face of the liquid chamber. The vibration member includes a metal member and a resin layer directly formed on the metal member, and the resin layer has a coefficient of linear expansion greater than a coefficient of linear expansion of the metal member.