Ink Droplet Registration Adjustment via Electrical Resistivity Measurement

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Solution Overview

Problem

Existing printing technologies face challenges in accurately adjusting ink droplet registration due to variations in ink ejection conditions and ink types, leading to potential inaccuracies in reading printed patterns and registration adjustments.

Innovation Solution

A printing apparatus and method that involves a print head, measurement unit, and control unit to measure optical characteristics of printed patterns, obtain adjustment values for dot positioning, and apply these values to adjust ink droplet placement accurately, regardless of ink ejection conditions or types, by using a combination of rough and fine adjustment processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If light color inks or yellow ink are used to reduce dot granularity, then dot quality is improved, but the S/N ratio in optical characteristic measurement decreases making pattern reading inaccurate

Engineering Contradiction:

Improvedot granularityVSAvoidS/N ratio in optical measurement

Core Design Contradiction:

Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The patent changes the measurement parameter from optical characteristic (reflectance) to electrical characteristic (resistivity). By measuring the electrical resistivity of the printed pattern instead of optical properties, the system can accurately measure light color inks and yellow ink without being limited by their high brightness and low optical contrast. This parameter substitution resolves the contradiction between dot quality and measurement accuracy.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If manufacturing variation and deterioration of print heads occur, then ink ejection characteristics change, but registration accuracy deteriorates

Engineering Contradiction:

Improveink ejection consistencyVSAvoidregistration accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent implements a feedback mechanism where the measured resistivity values from printed patterns are used to calculate registration adjustment values. These adjustment values are then applied to correct the print head positioning, creating a closed-loop system that compensates for manufacturing variations and deterioration over time, maintaining registration accuracy despite changes in ink ejection characteristics.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary measurement and adjustment operations using test patterns before actual printing. By pre-calculating registration adjustment values based on measured patterns and applying them in advance, the system compensates for print head variations before they affect production printing, ensuring consistent registration accuracy.

Inventive Principle:

Principle #10Preliminary action

3Extent of automation

If density-based pattern reading is used for registration adjustment, then adjustment values can be obtained, but reading accuracy decreases for light color inks and yellow ink

Engineering Contradiction:

Improveautomatic registration adjustmentVSAvoidpattern reading accuracy

Core Design Contradiction:

Extent of automationVSMeasurement precision

Solution Approach 1:

The patent replaces the optical measurement system with an electrical measurement system. Instead of using optical sensors to read pattern density, the system uses electrical resistivity measurement to detect printed patterns. This substitution enables automatic registration adjustment to work accurately with light color inks and yellow ink, as electrical measurement is not affected by ink brightness or optical properties.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 precise registration adjustment, ensuring accurate dot placement and pattern formation across various ink conditions and types, enhancing printing quality and reliability.

Implementation Method 1

a measurement unit configured to measure an optical characteristic of a print image printed on a print medium

Methodology Applied

Scientific EffectReflectance measurement: Reflection

Data Source

PatentUS11292268B2Printing apparatus, registration adjustment method, and storage medium

Publication Date: 2022.04.05 CANON KK

AI summary

A control unit controls a print head to print a print image by ejecting ink through a nozzle to form dots on a print medium and a movement unit to impart relative movement between the print head and the print medium to print a print image on the print medium. The control unit obtains a dot adjustment value in the predetermined print operation based on the measurement result of a measurement unit measuring a first pattern composed of a print image printed by the predetermined print operation including the relative movement, and a second adjustment value for adjusting dot printing positions in the predetermined print operation in a unit of length shorter than in the adjustment using the first adjustment value based on a second pattern printed by the predetermined print operation in a density according to density information on the first pattern, measured by the measurement unit.