Liquid Discharge Head Module Flow Layout for Uniform Ink Temperature

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Solution Overview

Problem

The temperature variation of liquid supplied to different liquid discharge heads in inkjet image forming apparatuses results in uneven viscosity, affecting the thickness and application position of the liquid, due to differing heating times based on varying distances from the liquid inlet to the outlets in the reservoir.

Innovation Solution

The implementation of a wall member in the liquid supply tank to redirect the liquid flow, equalizing the path lengths to the outlets and minimizing temperature differences between discharge heads, while maintaining the layout and preventing pressure fluctuations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If liquid is supplied from a single reservoir to multiple liquid discharge heads, then the device complexity is reduced, but the temperature of liquid to be supplied varies between the liquid discharge heads

Engineering Contradiction:
Improvedevice complexityVSAvoidtemperature of liquid
Core Design Contradiction:
Device complexityVSTemperature

Solution Approach 1:

The reservoir is divided into multiple heating zones with separate heating members, allowing independent temperature control for different liquid discharge heads. This segmentation enables each discharge head to receive liquid at the appropriate temperature despite varying flow path lengths.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the reservoir are provided with different heating characteristics through multiple heating members positioned at specific locations. This local quality adjustment ensures that liquid taking different paths receives appropriate heating to maintain consistent temperature at all discharge heads.

Inventive Principle:
Principle #3Local quality

2Temperature

If the distance from the inlet to the outlet in the reservoir is longer, then the liquid is heated for a longer time, but the temperature of the liquid to be supplied increases excessively

Engineering Contradiction:
Improvetemperature of liquidVSAvoidheating time
Core Design Contradiction:
TemperatureVSLoss of time

Solution Approach 1:

The heating process is segmented into multiple zones along the liquid flow path. Liquid takes different amounts of time to traverse different zones, and each zone provides appropriate heating. This prevents over-heating of liquid with long flow paths while ensuring sufficient heating for liquid with short flow paths.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The heating parameters (temperature, heating time) are changed dynamically based on the liquid flow path length. Heating members are positioned and controlled to provide different heating intensities and durations for liquid taking different paths from the inlet to various outlets.

Inventive Principle:
Principle #35Parameter changes

3Temperature

If the temperature of liquid to be supplied varies between liquid discharge heads, then the viscosity of liquid to be discharged varies, but this causes unevenness in the thickness of the liquid and shift in application position

Engineering Contradiction:
Improvetemperature of liquidVSAvoidapplication position accuracy
Core Design Contradiction:
TemperatureVSManufacturing precision

Solution Approach 1:

The reservoir is divided into multiple heating zones with separate heating members, allowing independent temperature control for different liquid discharge heads. This segmentation enables each discharge head to receive liquid at the appropriate temperature despite varying flow path lengths.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the reservoir are provided with different heating characteristics through multiple heating members positioned at specific locations. This local quality adjustment ensures that liquid taking different paths receives appropriate heating to maintain consistent temperature at all discharge heads.

Inventive Principle:
Principle #3Local quality

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 stabilizes the liquid temperature and viscosity across all discharge heads, ensuring consistent liquid discharge accuracy without altering the apparatus layout or causing pressure fluctuations.

Implementation Method 1

the liquid in the reservoir is heated by a heating member such as a heater

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

A wall member 27 that changes the flow direction of liquid is disposed in the supply tank 24

Methodology Applied
Scientific EffectFluid flow:

Data Source

PatentEP4378695B1Head module, image forming apparatus, and liquid discharge apparatus
Publication Date: 2025.12.31 RICOH CO LTD
  • EP4378695B1 patent drawingFigure 1
  • EP4378695B1 patent drawingFigure 2~3
  • EP4378695B1 patent drawingFigure 4~5

AI summary

Ahead module (20) includes at least two liquid discharge heads (21A, 21B), a reservoir (24), a heater (26), an inlet (50), a first outlet (51A), a second outlet (51B), and a wall member (27). The liquid discharge heads (21A, 21B) discharge liquid. The reservoir (24) stores the liquid. The heater (26) heats the liquid in the reservoir. The liquid is to be introduced from the inlet into the reservoir. The liquid in the reservoir is to be delivered from the first outlet to one (21A) of the liquid discharge heads. The liquid in the reservoir is to be delivered from the second outlet to another (21B) of the liquid discharge heads. A distance between the inlet and the first outlet (51A) is shorter than a distance between the inlet and the second outlet (51B). The wall member (27) is interposed between the inlet (50) and the first outlet (5 1A).