Print Head Ink Circulation Control for Monochrome-to-Color Reliability

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Solution Overview

Problem

Inkjet printing apparatuses face issues with increased ink viscosity near the ejection openings due to evaporation of volatile components, leading to ink concentration in circulation paths and potential ejection failures when switching from monochrome to color mode printing.

Innovation Solution

A printing apparatus with a control unit that manages ink circulation by circulating only the inks being used during printing and stopping circulation when not in use, and determines an accumulated time to decide when to circulate unused inks to prevent concentration and ensure proper ejection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If ink circulation is performed continuously for all ink types, then ink concentration is prevented, but ink viscosity increases near ejection openings due to evaporation

Engineering Contradiction:

Improveink concentrationVSAvoidink viscosity increase

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The circulation unit performs preliminary circulation of unused inks before switching from monochrome to color mode printing. This preliminary action prevents ink concentration and maintains proper ink flow characteristics, ensuring smooth transition between printing modes without ejection failures.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The circulation control is dynamically adjusted based on printing mode transitions. The circulation unit selectively circulates only unused inks when mode switching is detected, rather than maintaining continuous circulation of all inks. This dynamic control prevents viscosity increase while avoiding ink concentration.

Inventive Principle:

Principle #15Dynamics

2Stability of the object's composition

If chromatic color inks are not circulated during monochrome mode printing, then ink concentration is avoided, but viscosity increases near ejection openings

Engineering Contradiction:

Improveink concentrationVSAvoidejection reliability

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

Before switching from monochrome to color mode, the circulation unit performs preliminary circulation of the chromatic color inks that were not circulated during monochrome printing. This preliminary action restores proper ink flow characteristics and prevents ejection failures when color printing begins.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control unit monitors printing mode transitions and uses this feedback to trigger selective ink circulation. When a mode switch from monochrome to color is detected, the system automatically initiates circulation of the previously unused chromatic inks, ensuring reliable ejection.

Inventive Principle:

Principle #23Feedback

3Use of energy by moving object

If ink circulation is stopped when not in use, then energy consumption is reduced, but ink concentration occurs in the circulation path

Engineering Contradiction:

Improveenergy consumptionVSAvoidink concentration

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The system performs preliminary circulation of unused inks before mode switching occurs. This brief preliminary circulation prevents ink concentration without requiring continuous circulation, thus maintaining low energy consumption while ensuring ink quality when needed.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of continuous circulation, the system employs periodic circulation triggered by mode switching events. The circulation unit operates intermittently - circulating inks only when printing mode changes - which prevents concentration while minimizing energy consumption during steady-state printing.

Inventive Principle:

Principle #19Periodic 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 solution effectively prevents ink concentration and ejection failures by ensuring that unused inks are circulated before switching to color mode printing, maintaining print quality and reliability.

Implementation Method 1

increase in viscosity of ink near the ejection openings of the print head due to evaporation of volatile components in the ink from the ejection openings

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS12344006B2Printing apparatus and method of controlling printing apparatus

Publication Date: 2025.07.01 CANON KK

AI summary

A printing apparatus comprises: a print head comprising, for each of a plurality of types of inks, an ejection opening and pressure chamber, and configured to perform printing operation by ejecting the ink from the ejection opening; a circulation unit capable of circulating the ink of each ink type; a determination unit configured to determine an accumulated time for which a first type of ink is circulated by the circulation unit in the printing operation using the first type of ink and not using a second type of ink different from the first type of ink; and a control unit configured to perform control based on the determined accumulated time to cause the circulation unit to circulate at least the second type of ink among the plurality of types of inks in a case where the accumulated time is longer than a predetermined time.