Piezoelectric Ink Stirring via Phase-Shifted Drive Signals

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing droplet discharge technologies face challenges in effectively stirring liquids in droplet discharge heads, particularly with nonaqueous solvent-based inks and UV curing inks, due to increased ink viscosity and precipitation issues, which affect droplet size and nozzle clogging.

Innovation Solution

The method involves using piezoelectric elements to create pressure differences across flow channels in a droplet discharge head, allowing for efficient stirring of liquids even when the elements are driven with insufficient force to discharge droplets, by varying drive conditions and synchronously driving elements in opposite phases to maximize pressure differences and flow distances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If microvibration is induced in the meniscus at pressure insufficient for ink discharge, then ink viscosity is maintained in the nozzle opening, but stirring in the ink channel is extremely difficult and insufficient

Engineering Contradiction:

Improveink viscosity maintenanceVSAvoidstirring effectiveness in ink channel

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent divides the drive control into different pressure levels: a first pressure range for stirring the ink channel (insufficient for discharge) and a second pressure range for discharging droplets. This segmentation allows independent optimization of stirring and discharge functions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies preliminary stirring action to the ink channel before droplet discharge. By stirring the ink channel in advance at a pressure insufficient for discharge, the ink is pre-mixed and ready for subsequent discharge without precipitation issues.

Inventive Principle:

Principle #10Preliminary action

2Ease of operation

If piezoelectric elements are driven with force insufficient to discharge droplets, then liquid flow is generated for stirring, but stirring efficiency is limited

Engineering Contradiction:

Improveliquid flow generationVSAvoidstirring efficiency

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The patent applies periodic drive signals to the piezoelectric elements to generate oscillating liquid flow. This periodic action creates back-and-forth movement of the liquid meniscus, enhancing mixing efficiency without requiring continuous high-pressure discharge.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent changes the drive pressure parameter between two ranges: a first pressure range for stirring (insufficient for discharge) and a second pressure range for discharge. This parameter switching enables the system to achieve both stirring and discharge functions with the same piezoelectric elements.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If nozzle opening size is reduced to prevent precipitation, then droplet size control is improved, but nozzle clogging risk increases

Engineering Contradiction:

Improvedroplet size controlVSAvoidnozzle clogging resistance

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent maintains continuous stirring action in the ink channel through periodic drive signals. This continuous mixing prevents pigment precipitation and maintains ink homogeneity, reducing nozzle clogging risk while enabling precise droplet size control.

Inventive Principle:

Principle #20Continuity of useful 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 approach enables effective stirring of liquids within the droplet discharge head, reducing precipitation and improving ink discharge quality, even in cases where conventional microvibration is insufficient, thereby enhancing the reliability and performance of droplet discharge systems.

Implementation Method 1

droplets of the liquid are discharged from a plurality of nozzle openings by driving piezoelectric elements provided to each of the nozzle openings

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

different pressures are applied to the liquid in the flow channels that correspond to each nozzle opening in the head

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentUS8567917B2Method of stirring liquid in droplet discharge head and droplet discharge apparatus

Publication Date: 2013.10.29 KATEEVA INC

AI summary

In a method of stirring liquid in a droplet discharge head in which droplets of the liquid are discharged from a plurality of nozzle openings by driving piezoelectric elements provided to each of the nozzle openings, drive conditions of the piezoelectric elements are varied and the liquid that corresponds to the piezoelectric elements is caused to flow at different pressures.