Aligning Clear Ink Printheads Using Colored Test Patterns

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Solution Overview

Problem

Existing inkjet printing systems struggle to align printheads that eject clear ink due to the difficulty in detecting clear ink drops, as they do not image well, making it challenging to infer the positions and orientations of these printheads.

Innovation Solution

A method and system that involve printing a first test pattern with colored ink and a second test pattern with clear ink over the first, allowing for data collection on misalignment, which is then used to adjust the alignment of the clear ink printheads relative to colored ink printheads using actuators controlled by a controller.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If clear ink is used for printing, then image quality and gloss are improved, but detection of ink drops becomes difficult

Engineering Contradiction:

Improveimage qualityVSAvoiddetection of clear ink drops

Core Design Contradiction:

Illumination intensityVSDifficulty of detecting and measuring

Solution Approach 1:

A colored test pattern is printed first to serve as a background, and clear ink is printed over it. The clear ink modifies the appearance of the colored pattern beneath, creating an intermediary effect that allows detection. The colored test pattern acts as a mediator that makes the invisible clear ink drops detectable through changes in color, reflectivity, or texture of the underlying pattern.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The method relies on color changes to detect clear ink drops. A colored test pattern is printed first, then clear ink is printed over it. The clear ink alters the appearance of the colored pattern through changes in color, reflectivity, or texture. By detecting these color changes in the combined pattern, the system can locate clear ink drops and calculate printhead position and orientation.

Inventive Principle:

Principle #32Color changes

2Manufacturing precision

If clear ink printheads are aligned using traditional methods, then alignment precision is improved, but detection capability deteriorates due to clear ink invisibility

Engineering Contradiction:

Improveprinthead alignment precisionVSAvoidclear ink drop detection

Core Design Contradiction:

Manufacturing precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The method performs preliminary action by printing a colored test pattern before printing clear ink. This preliminary colored pattern serves as a detection background that enables subsequent detection of clear ink drops. The test pattern is printed first, then clear ink is printed over it, allowing the system to detect clear ink location through modifications to the pre-existing colored pattern.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The colored test pattern acts as an intermediary that enables detection of clear ink drops. By printing a visible colored pattern first and then printing clear ink over it, the system creates an intermediary layer that modifies the appearance of the colored pattern. This intermediary effect allows the detection system to locate clear ink drops and calculate printhead position and orientation despite the clear ink's invisibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If test patterns are printed with both colored and clear ink, then alignment data accuracy is improved, but printing complexity increases

Engineering Contradiction:

Improvealignment data accuracyVSAvoidprinting process complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The method merges the printing of colored ink and clear ink into a single integrated process. A colored test pattern is printed first, then clear ink is printed over it in a sequential manner. This merging approach allows the system to collect alignment data for both colored and clear ink printheads simultaneously, improving alignment data accuracy while managing printing process complexity through systematic integration.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The test pattern serves multiple functions: it acts as a detection background for clear ink drops, provides reference points for calculating printhead position and orientation, and enables alignment verification for both colored and clear ink printheads. By making the test pattern multi-functional, the system improves measurement precision without proportionally increasing printing process complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS8506038B2Method and system for aligning printheads that eject clear ink in an inkjet printer

Publication Date: 2013.08.13 XEROX CORP

AI summary

A method enables an operator to detect misalignment of printheads that eject clear ink in an inkjet printer. The method prints a first test pattern with a first color of ink and then prints a second test pattern of clear ink on top of the first test pattern. The ink of the first and the second test patterns is then spread to enable the clear ink to be dispersed in interstitial spaces in the ink of the first color. An operator is then able to detect the spatial relationship of predetermined marks in the second test pattern to predetermined marks in the first test pattern. The predetermined marks of the first and the second test patterns are arranged to enable an operator to detect a misalignment distance and the inkjet printer uses the misalignment distance entered by the operator to adjust the alignment of the printheads that eject clear ink.