Inkjet Head Pass Sequence for Electrostatic Charge Control
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Solution Overview
Problem
Ink jet printers using colored inks and clear inks experience image blurs and haze due to electrostatic charges on film-type printing media, which are exacerbated by the mixing of ancillary clear ink with image forming ink, leading to satellite formation and image degradation.
Innovation Solution
A printing apparatus with a control unit that separates the ejection of image forming liquid and ancillary liquid onto distinct regions of the printing medium, with the ancillary liquid ejected in an anterior pass and the image forming liquid in a posterior pass, allowing for controlled ejection and reduced mixing, and includes a calculation unit to adjust the ancillary liquid ejection based on coverage ratio and humidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If an ancillary liquid (clear ink) is applied to the entire surface of a printing medium in advance to reduce electrostatic charges, then the uniformity of electrostatic charges is improved, but the image quality deteriorates due to mixing with image forming liquid causing blurs
Solution Approach 1:
The printing process is divided into two separate passes: a first pass that applies ancillary liquid only to non-image regions, and a second pass that applies image forming liquid only to image regions. This segmentation prevents mixing between the two liquids while still achieving the benefit of electrostatic charge reduction in non-image areas.
Solution Approach 2:
The ancillary liquid is applied in advance during a first pass before the image forming liquid is applied in a second pass. This preliminary action allows the ancillary liquid to reduce electrostatic charges on the printing medium before the image forming process, preventing satellite formation while avoiding subsequent mixing issues.
2Productivity
If the head ejects both image forming liquid and ancillary liquid simultaneously, then the processing efficiency is improved, but the image quality deteriorates due to mixing of liquids
Solution Approach 1:
The ejection process is segmented into two distinct passes: the first pass ejects ancillary liquid onto non-image regions, and the second pass ejects image forming liquid onto image regions. This temporal and spatial segmentation eliminates liquid mixing while maintaining comprehensive coverage of the printing medium.
Solution Approach 2:
The printing process uses periodic action by alternating between two distinct ejection passes. The first pass handles ancillary liquid application, followed by the second pass for image forming liquid application. This periodic approach ensures that the two liquids never contact each other, preventing blurs while still achieving complete surface treatment.
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 solution effectively reduces image blurs and satellite formation by ensuring uniform electrostatic charges and minimizing the mixing of ancillary and image forming inks, improving image quality even during low coverage ratio and low humidity conditions.
Implementation Method 1
a film type medium is likely to, inside a printer, cause electrostatic charges on its surface due to a friction with a paper-feeding roller
Data Source
AI summary
Provided is a printing apparatus including a head and a control unit. The head ejects, onto a printing medium, an image forming liquid for forming an image and an ancillary liquid ancillary to forming of the image performed by the image forming liquid. The control unit performs control so as to cause the head to perform a first operation of ejecting the image forming liquid onto a first region of the printing medium, and a second operation of ejecting the ancillary liquid onto a second region of the printing medium, the second region being different from the first region. Further, the control unit performs control so as to cause the head to perform the second operation in an anterior pass and perform the first operation in a posterior pass.