Eddy Current Primer Thickness Control for Inkjet Image Quality

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Solution Overview

Problem

Inkjet printers face challenges in effectively and efficiently applying primers to media, particularly uncoated media, due to primer absorption into fibers, difficulty in detecting primer application, and the additional load on image dryers, leading to inefficient primer regulation and image quality issues.

Innovation Solution

A color inkjet printer equipped with a primer applicator, sensor, and controller that measures primer thickness and adjusts operation to maintain optimal primer application, using an eddy current sensor to detect primer on media and regulate primer applicator operation based on identified thickness ranges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If primer is applied to uncoated media, then image quality is improved by reducing ink absorption into fibers, but the amount of primer required increases and the load on image dryers increases due to additional water evaporation

Engineering Contradiction:

Improveimage qualityVSAvoidprimer amount

Core Design Contradiction:

Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The system uses a sensor to detect primer thickness on the media and provides feedback to the controller, which adjusts the primer applicator operation to maintain optimal primer application. This closed-loop control ensures that the correct amount of primer is applied without waste or deficiency.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts primer application parameters based on media type detection. The controller modifies primer thickness, application speed, or applicator pressure to optimize primer deposition for different media types (coated vs. uncoated), thereby improving image quality while minimizing primer consumption.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If primer is applied to uncoated media, then image quality is improved, but the load on image dryers increases due to additional water evaporation required

Engineering Contradiction:

Improveimage qualityVSAvoidimage dryer load

Core Design Contradiction:

Manufacturing precisionVSUse of energy by stationary object

Solution Approach 1:

The sensor provides real-time feedback on primer thickness to the controller, which adjusts drying parameters accordingly. When optimal primer thickness is detected, the dryer operates at reduced capacity, minimizing energy consumption while still achieving proper drying.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system applies only the necessary amount of primer (not excessive) and adjusts dryer operation to provide just enough drying capacity for the actual primer load, avoiding both under-drying and over-drying scenarios that waste energy.

Inventive Principle:

Principle #16Partial or excessive action

3Extent of automation

If optical image generators are used to detect primer on media, then primer thickness measurement is required for regulation, but measurement accuracy is poor because primers are typically clear and difficult to detect

Engineering Contradiction:

Improveprimer regulationVSAvoidprimer thickness measurement

Core Design Contradiction:

Extent of automationVSMeasurement precision

Solution Approach 1:

The system replaces optical detection methods with an eddy current sensor that uses electromagnetic fields to measure primer thickness. This non-optical approach can detect clear or transparent primer coatings accurately by measuring changes in electromagnetic properties rather than relying on optical contrast.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system changes the detection parameter from optical properties (which fail for clear primers) to electromagnetic properties. The eddy current sensor measures electrical conductivity or magnetic permeability changes caused by the primer layer, providing accurate measurement regardless of the primer's optical transparency.

Inventive Principle:

Principle #35Parameter changes

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

Enables accurate and efficient primer application, improving image quality and reducing the load on image dryers by optimizing primer thickness, thus enhancing the recycling potential of printed media.

Implementation Method 1

using an eddy current sensor to detect primer on media and regulate primer applicator operation based on identified thickness ranges

Methodology Applied

Scientific EffectEddy current: Eddy Currents

Data Source

PatentUS20250222708A1System and method for measuring primer parameters in inkjet printers

Publication Date: 2025.07.10 XEROX CORP

AI summary

An inkjet printer includes a primer applicator to apply primer to media before the media is printed and includes a plurality of eddy current sensors to identify a thickness of the primer on the media. The identified thickness is compared to a range of acceptable primer thicknesses. One end of the range of acceptable thicknesses corresponds to a thickness that is too thin to enable deinking of the printed media and the other end of the range of acceptable thicknesses corresponds to a thickness that is too thick to enable sufficient drying to fix the ink image to the media. In one embodiment, the primer is applied using a printhead that eject drops of primer onto the media.