Liquid Circulation Control for Stable Inkjet Head Pressure

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Solution Overview

Problem

Existing liquid circulation systems in liquid discharge heads experience pressure fluctuations during operation, leading to instability in liquid circulation and potential issues such as dripping or bubble formation, which affect printing quality.

Innovation Solution

A liquid circulation device with a controller that adjusts the amount of liquid feed based on discharge information, using supply and collection pumps to maintain stable pressure by anticipating discharge operations and adjusting liquid flow before and after printing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If liquid is circulated by pressure difference in a circulatory head, then liquid circulation is enabled, but pressure fluctuation occurs during liquid discharge operation

Engineering Contradiction:
Improveliquid circulation stabilityVSAvoidpressure fluctuation
Core Design Contradiction:
ReliabilityVSStress or pressure

Solution Approach 1:

The controller adjusts the liquid feed amount in advance based on discharge information before liquid discharge occurs. By anticipating the discharge operation and pre-adjusting the liquid supply, the system prepares the circulation path for upcoming pressure changes, thereby reducing the magnitude of pressure fluctuations during actual discharge operations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses discharge information about the liquid to be discharged from the liquid discharge head to control the amount of liquid fed by the liquid feeding device. This feedback mechanism allows the controller to adjust liquid feed based on actual discharge conditions, maintaining more stable pressure in the circulation path despite varying discharge operations.

Inventive Principle:
Principle #23Feedback

2Reliability

If pressure fluctuation is reduced for stable liquid circulation, then circulation stability improves, but control complexity increases

Engineering Contradiction:
Improveliquid circulation stabilityVSAvoidcontrol system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The controller receives discharge information from the liquid discharge head and automatically adjusts the liquid feed amount accordingly. This closed-loop feedback control enables the system to maintain stable liquid circulation without requiring complex manual intervention or additional hardware components, achieving reliability improvement with manageable control complexity.

Inventive Principle:
Principle #23Feedback

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

Stable liquid circulation is achieved, reducing pressure fluctuations and preventing dripping or bubble formation, thereby improving printing quality and reliability.

Implementation Method 1

liquid is circulated by a pressure difference between the liquid supply side and the liquid collection side with respect to the head

Methodology Applied
Scientific EffectPressure difference: Pressure Gradient

Data Source

PatentEP3653388B1Liquid circulation device, and liquid discharge apparatus including the liquid circulation device
Publication Date: 2026.02.25 RICOH CO LTD
  • EP3653388B1 patent drawingFigure 1
  • EP3653388B1 patent drawingFigure 2~3
  • EP3653388B1 patent drawingFigure 4

AI summary

A liquid circulation device (200) includes a circulation path (210), a liquid feeding device (212, 213), and a controller (400). The circulation path (210) is configured to circulate a liquid to be supplied to a liquid discharge head (100) of a circulatory type and collected from the liquid discharge head (100). The liquid feeding device (212, 213) is configured to feed the liquid to circulate the liquid in the circulation path (210). The controller (400) is configured to control an amount of the liquid to be fed by the liquid feeding device (212, 213), on a basis of discharge information about the liquid to be discharged from the liquid discharge head (100).