Inkjet Print Head Temperature Control for Density Uniformity

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Solution Overview

Problem

Existing ink jet printing technologies face issues with head temperature variations leading to density variations in printed images, as prior art methods often set target temperatures based on stable ejection temperatures or temperatures at scan completion, resulting in excessive temperature rises or drops, causing significant density differences between scans.

Innovation Solution

An ink jet printing apparatus and method that adjusts the print head temperature at the start of each scan to a target temperature differing by a predetermined value from the temperature at the completion of the previous scan, using a head temperature acquisition unit and temperature control unit to maintain a stable temperature range and minimize density variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the target temperature is set to the stable ejection temperature, then the ink ejection stability is improved, but the head temperature rises excessively causing density variation in printed images

Engineering Contradiction:

Improveink ejection stabilityVSAvoidprint density uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies dynamics by making the target temperature adjustable rather than fixed. The target temperature is dynamically determined based on the actual head temperature at scan completion, allowing the system to adapt to varying thermal conditions. This resolves the contradiction by preventing excessive temperature rises that would occur with a fixed stable ejection temperature target, thereby maintaining both ejection stability and print density uniformity.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements feedback control by using the actual head temperature at scan completion as the basis for determining the next target temperature. This feedback mechanism allows the system to respond to actual thermal conditions rather than following a predetermined temperature schedule, preventing cumulative temperature rises and maintaining consistent print quality across multiple scans.

Inventive Principle:

Principle #23Feedback

2Ease of operation

If the target temperature is set to the head temperature at scan completion, then the temperature control follows the prior art method, but the head temperature drops significantly causing density variation between scans

Engineering Contradiction:

Improvetemperature control simplicityVSAvoidprint density uniformity

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by heating the head to a target temperature before the scan begins, rather than relying on the temperature at scan completion. This preliminary heating ensures the head reaches an optimal temperature range before printing, preventing significant temperature drops during the scan and maintaining density uniformity across scans.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the temperature parameter dynamically by setting the target temperature based on the actual head temperature at scan completion rather than using a fixed value. This parameter adjustment prevents excessive temperature drops and maintains consistent print quality while preserving the simplicity of the control method.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If heating is carried out to reach stable ejection temperature, then the ejection stability is improved, but the head temperature becomes higher than necessary causing energy waste and temperature instability

Engineering Contradiction:

Improveejection stabilityVSAvoidheating energy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies partial action by heating the head only to the necessary target temperature rather than always reaching the stable ejection temperature. When the head temperature is already close to the stable ejection temperature, minimal or no heating is applied, reducing energy consumption while maintaining sufficient ejection stability for quality printing.

Inventive Principle:

Principle #16Partial or excessive 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 approach effectively inhibits excessive head temperature rises and density variations by setting a target temperature within a 5°C range of the previous scan's completion temperature, ensuring consistent print quality across scans.

Implementation Method 1

heating is carried out

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 2

the temperature of the ink in the print head has been controlled

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS9545791B2Ink jet printing apparatus and print head temperature control method

Publication Date: 2017.01.17 CANON KK

AI summary

When the head temperature Tfinish, which is the head temperature at the time of completion of a preceding scan, is higher than the stable ejection temperature Tstable, the target temperature is made a temperature that is only a temperature value ΔT lower than the head temperature Tfinish. On the other hand, when Tfinish, the head temperature at the time of print completion, is lower than the stable ejection temperature Tstable, the target temperature is made a temperature that is only a temperature value ΔT higher than the head temperature Tfinish. Because of this it is possible to inhibit head temperature rise in the case where an image with a high print density is printed.