Opposite Ink Flow Printhead Orientation for Stitch Area Uniformity

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Solution Overview

Problem

Inkjet printers face image quality degradation due to temperature gradients in ink within printheads, particularly in stitch areas between adjacent printheads, leading to perceptible differences in ink drop appearance and color density.

Innovation Solution

The printer is configured with printheads oriented such that ink flowing through the manifolds of adjacent printheads moves in opposite directions, reducing the temperature differential between ink drops ejected into stitch areas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If inkjets in a printhead are operated to eject ink for high ink coverage areas, then the demand for ink in the printhead increases and more ink is pulled through the manifold, but the ink becomes heated non-uniformly creating temperature differentials that cause smaller cooler ink drops to be ejected, appearing lighter than warmer ink drops

Engineering Contradiction:

Improveink coverage capabilityVSAvoidink drop uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent reverses the conventional approach by orienting adjacent printheads to flow ink in opposite directions through their manifolds. This inversion causes the temperature gradients to develop in opposite directions across adjacent printheads, so that when ink is ejected at stitch areas between printheads, the temperature differentials partially cancel each other out, resulting in more uniform ink drop appearance.

Inventive Principle:

Principle #13The other way round (Inversion)

2Adaptability or versatility

If multiple printhead modules are positioned in a process direction to eject different colors of ink, then color image production is enabled, but temperature gradients develop in the ink within each printhead during print jobs, creating perceptible differences in ink drop appearance at boundaries between stitch areas

Engineering Contradiction:

Improvecolor image production capabilityVSAvoidimage quality uniformity

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent applies reverse orientation to adjacent printheads within the multi-color printhead modules. By configuring ink to flow in opposite directions through adjacent printhead manifolds, the temperature gradients that would normally accumulate in the same direction are instead created in opposite directions, causing partial cancellation of temperature differentials at stitch area boundaries and improving overall image quality uniformity.

Inventive Principle:

Principle #13The other way round (Inversion)

3Temperature

If ink flows through the manifold from the ink supply end to the printhead end, then ink is heated to operational temperature, but a temperature differential is produced between the heated ink at the manifold outlet and the cooler ink at the inkjets farthest from the manifold outlet

Engineering Contradiction:

Improveink heating efficiencyVSAvoidtemperature uniformity

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

The patent reverses the conventional single-direction heating approach by implementing opposite direction ink flow through adjacent printhead manifolds. This causes temperature gradients to develop in opposite directions, so that when ink is ejected at boundaries between adjacent printheads, the temperature differentials partially cancel each other out, resulting in more uniform ink temperature and appearance.

Inventive Principle:

Principle #13The other way round (Inversion)

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 minimizes the color density shifts between printheads, resulting in more uniform ink drop appearance and improved image quality by reducing the temperature differential in stitch areas.

Implementation Method 1

A heater extends the length of the manifold to heat the ink as the ink flows from the end coupled to the ink supply to the opposite end of the manifold where the ink moves through the printhead

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 2

Each inkjet has a thermal or piezoelectric actuator that is coupled to a printhead controller. The actuators in the printheads respond to the firing signals by expanding into an ink chamber of the inkjet to eject ink drops

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS12296585B2System and method for improving image quality by orienting adjacent printheads to produce opposite direction ink flows in the manifolds of the adjacent printheads

Publication Date: 2025.05.13 XEROX CORP

AI summary

An inkjet printer configures the printheads in a printhead module in an orientation that attenuates a temperature differential between the ink drops ejected by adjacent printheads at a stitch area between the adjacent printheads. The reduced temperature differential helps ensure that the contrasts between the two inks ejected by the adjacent printheads is sufficiently similar that image quality is not adversely impacted.