Liquid Discharge Apparatus Height Adjuster UV Curing

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Solution Overview

Problem

Conventional UV-curable ink curing methods result in image quality degradation due to curing shrinkage, leading to wrinkles at the boundary between cured and uncured portions, especially when multiple UV irradiations are required to cover larger image areas.

Innovation Solution

A liquid discharge apparatus with a height adjuster that adjusts the irradiation distance based on the maximum width of the liquid surface, allowing for uniform UV light irradiation and reducing the need for multiple passes, thereby minimizing curing shrinkage-induced wrinkles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If UV irradiation is performed multiple times to cover larger image areas, then the irradiation coverage is improved, but wrinkles are created at the boundary between cured and uncured portions due to curing shrinkage

Engineering Contradiction:
Improveirradiation coverage areaVSAvoidimage quality
Core Design Contradiction:
Area of stationary objectVSManufacturing precision

Solution Approach 1:

The patent divides the irradiation process into multiple sequential passes, where each pass irradiates a portion of the liquid surface. The key is that subsequent passes irradiate previously uncured portions while the previously cured portions act as stable boundaries, preventing wrinkle formation at boundaries during the multi-pass process

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary curing of portions of the liquid surface before completing the entire irradiation process. By curing portions sequentially and allowing them to stabilize before moving to adjacent uncured portions, the system prevents shrinkage-induced wrinkles from forming at boundaries during the multi-pass irradiation process

Inventive Principle:
Principle #10Preliminary action

2Ease of operation

If UV-curable ink is cured before becoming smooth, then a matte feel image is formed, but the image surface quality is reduced

Engineering Contradiction:
Improvecuring timing controlVSAvoidimage surface quality
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent uses periodic irradiation cycles where the UV irradiation is applied in intervals rather than continuously. This allows the liquid surface to smooth between irradiation cycles while still achieving complete curing, thereby maintaining image surface quality while controlling the curing process

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent allows the UV-curable ink to smooth on the liquid surface before applying UV irradiation. This preliminary smoothing action occurs during the discharge and settling phase, ensuring the liquid surface achieves a smooth state before curing begins, thus preventing matte feel images

Inventive Principle:
Principle #10Preliminary 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

Prevents image quality deterioration by ensuring uniform curing across the entire liquid surface, reducing the formation of wrinkles and maintaining image quality regardless of curing shrinkage, even when the UV light cannot irradiate the entire surface in a single pass.

Implementation Method 1

UV-curable ink is discharged onto a medium and irradiated and cured with UV light to form an image

Methodology Applied
Scientific EffectUV irradiation: Photopolymerisation

Data Source

PatentEP3354472B1Liquid discharge apparatus, liquid curing method, and computer program product
Publication Date: 2019.06.26 RICOH CO LTD
  • EP3354472B1 patent drawingFigure 1
  • EP3354472B1 patent drawingFigure 2
  • EP3354472B1 patent drawingFigure 3

AI summary

A liquid discharge apparatus includes a liquid discharge head (300) to discharge liquid to a medium (101) to form liquid surface on the medium (101), an irradiator (400) to radiate active energy rays onto the liquid surface, a carriage (200) mounting the liquid discharge head (300) and the irradiator (400), a scanner (206) to scan the carriage in a main scanning direction, a height adjuster (207) to adjust an irradiation distance between the irradiator (400) and the liquid surface by relatively moving the carriage (200) and the medium (101), a conveyor (100) to move the medium (101) and the carriage (200) relatively in a sub-scanning direction perpendicular to the main scanning direction, and control circuitry to control the irradiator (400) to irradiate the liquid surface with the active energy rays while scanning the carriage (200) in the main scanning direction.