Ink Circulation Device Bypass Filter Bubble Management

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Solution Overview

Problem

In inkjet recording devices using piezoelectric pumps, miniaturization leads to increased pressure loss and reduced ink circulation flow rates due to bubble accumulation in air trap filters, causing ejection failures as bubbles pass through the filter with the ink.

Innovation Solution

An ink circulation device with a filter and a bypass section that partitions the ink flow path, catching bubbles in the filter while directing excess air through a bypass section to maintain stable ink flow and prevent pressure loss, using a piezoelectric pump with a piezoelectric actuator and a filter like a metal sheet or resin membrane.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the device is miniaturized using a piezoelectric pump, then compactness is improved, but bubbles generate easily in the pressure chamber and accumulate in the filter

Engineering Contradiction:
Improvedevice sizeVSAvoidbubble generation
Core Design Contradiction:
Volume of moving objectVSObject-generated harmful factors

Solution Approach 1:

The harmful bubbles are extracted from the ink flow by introducing a dedicated bypass flow path that separates bubble removal from the main ink circulation. The bypass section with opening forming section creates a specific flow route that extracts accumulated bubbles from the upstream side of the filter without disrupting the main ink supply to the nozzles.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The bypass section acts as an intermediary element between the filter upstream side and the downstream side ink flow path. It provides a mediating flow path that allows bubbles to be redirected away from the filter while maintaining the filtering function, thus resolving the conflict between compact filtration and bubble accumulation.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If air is accumulated at the upstream side of the filter, then bubble trapping is improved, but contact area of ink and filter decreases and pressure loss increases

Engineering Contradiction:
Improvebubble trappingVSAvoidpressure loss
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The ink flow path is segmented into multiple independent paths: the main flow path through the filter for bubble trapping, and the bypass flow path for pressure relief and bubble removal. This segmentation allows the system to maintain both effective filtration and adequate ink flow by directing excess air and pressure through the bypass route.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system dynamically adjusts flow distribution between the filter path and bypass path based on operating conditions. When bubble accumulation increases pressure at the upstream side, the bypass section automatically activates to relieve pressure, creating a dynamic balance between filtration effectiveness and pressure loss prevention.

Inventive Principle:
Principle #15Dynamics

3Productivity

If pressure at upstream side of filter exceeds bubbles point pressure, then bubbles pass through filter with ink, but ejection failure occurs

Engineering Contradiction:
Improveink circulation flow rateVSAvoidejection stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The bypass section is positioned and configured to activate before pressure reaches the critical bubbles point pressure level. The opening forming section creates a flow path that preemptively redirects excess air and pressure away from the filter, preventing the condition where bubbles would force their way through the filter with the ink and cause ejection failures.

Inventive Principle:
Principle #10Preliminary 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 maintains stable ink circulation flow rates and prevents ejection failures by managing bubble accumulation and pressure loss, ensuring consistent inkjet performance even in miniaturized devices.

Implementation Method 1

the ink circulation pump is a piezoelectric pump for driving a piezoelectric actuator with a piezoelectric element

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

a filter positioned to partition an upstream side ink flow path arranged between an ejection section of the ink circulation pump and the ink supply into a first flow path communicating with the ejection section of the ink circulation pump and a second flow path communicating with the ink supply, and configured to catch bubbles in the ink in the first flow path

Methodology Applied
Scientific EffectPhysical filtration: Filter (physical)

Data Source

PatentEP3228463B1Ink circulation device and inkjet recording device
Publication Date: 2020.04.22 TOSHIBA TEC KK
  • EP3228463B1 patent drawingFigure 1
  • EP3228463B1 patent drawingFigure 2
  • EP3228463B1 patent drawingFigure 3

AI summary

In accordance with an embodiment, an ink circulation device comprises an ink supply section, an ink return section, an ink circulation pump, a filter and a bypass section. The filter partitions an upstream side ink flow path arranged between an ejection section of the ink circulation pump and the ink supply section into a first flow path communicating with the ejection section of the ink circulation pump and a second flow path communicating with the ink supply section. The bypass section is arranged at the upper part of a vertical direction with respect to the filter, directly communicates the first flow path with a downstream side ink flow path arranged between the ink return section and a suction section of the ink circulation pump. An inkjet recording device of the present embodiment comprises the foregoing ink circulation device.