Liquid Ejection Head With Alternating Ink Ejection And Circulation

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Solution Overview

Problem

Existing liquid ejection systems, such as those described in Japanese Patent Laid-Open No. 2020-104312, require pressure adjustment mechanisms and pumps for ink circulation, leading to increased size of the printing apparatus and inefficiencies.

Innovation Solution

A liquid ejection head and method utilizing a separate ejection unit with a first and second heat energy generating element, controlled to drive mutually exclusively, and a driving circuit to optimize data usage, allowing for efficient ink circulation without the need for external pumps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a differential pressure system with pressure adjustment mechanism and pump is used for ink circulation, then ink circulation is achieved, but the printing apparatus and head are upsized

Engineering Contradiction:

Improveink circulationVSAvoidprinting apparatus size

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The invention extracts the pump function from the external circulation system and integrates it into the head as a flow energy generating element. This eliminates the need for external pressure adjustment mechanisms and pumps, thereby reducing the overall apparatus size while maintaining ink circulation capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention merges the ejection function and circulation function into a single integrated head structure. The flow energy generating element is disposed within the head to drive ink circulation, combining multiple functions (ejection and circulation) into one compact unit, thus avoiding apparatus upsizing.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If a pump is provided inside the liquid ejection head for ink circulation, then ink circulation is achieved, but the head structure becomes more complex

Engineering Contradiction:

Improveink circulationVSAvoidhead structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention replaces the mechanical pump system with a flow energy generating element that utilizes thermal or other energy conversion mechanisms. This substitution simplifies the head structure by eliminating complex mechanical components while achieving the same ink circulation function.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If both first and second heat energy generating elements are driven simultaneously, then ejection and circulation occur, but energy is wasted and ejection stability is compromised

Engineering Contradiction:

Improveejection and circulationVSAvoidenergy consumption

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The invention implements periodic alternation between driving the first heat energy generating element (for ejection) and the second heat energy generating element (for circulation). By controlling them to operate at different times rather than simultaneously, the system achieves both ejection and circulation functions while minimizing energy waste and maintaining ejection stability.

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

The solution enables optimized data usage and efficient ink circulation, reducing the size of the printing apparatus and improving throughput and yield by minimizing waste ink and maintaining ejection stability.

Implementation Method 1

a first heat energy generating element provided for the pressure chamber and configured to generate heat energy for ejecting a liquid from the ejection orifice

Methodology Applied

Scientific EffectHeat energy generation: Heating

Implementation Method 2

a second heat energy generating element provided for the separate flow path

Methodology Applied

Scientific EffectHeat energy generation: Heating

Data Source

PatentUS20250289219A1Liquid ejection head and liquid ejection method

Publication Date: 2025.09.18 CANON KK

AI summary

A liquid ejection method uses: a separate ejection unit including an ejection orifice, a pressure chamber, a first heat energy generating element provided for the pressure chamber, a separate flow path communicating with the pressure chamber, and a second heat energy generating element provided for the separate flow path; and a liquid ejection head including a common flow path for supplying a liquid to the plural separate flow paths of the plural separate ejection units. In drive control of the first heat energy generating element and the second heat energy generating element, when the first heat energy generating element is driven, the second heat energy generating element is not driven, and, when the first heat energy generating element is not driven, the second heat energy generating element is driven upon receiving a driving signal that instructs drive relative to the second heat energy generating element.