Full Color Printing via 1-Bit Halftoning and Non-Transparent Inks
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Solution Overview
Problem
Conventional full-color printing methods require transparent or semi-transparent inks for ink trapping, leading to issues like ink contamination, poor drying, and excessive ink usage, especially on substrates that are not tolerant of high ink coverage.
Innovation Solution
A method for color separation and printing that eliminates ink traps by converting CMYK digital images to 1-bit files, using non-transparent inks, and performing specific merging and inversion steps to create unique separations, allowing for full-color printing without ink drying between stations and reducing ink usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If transparent or semi-transparent inks are used for ink trapping, then full colour images can be printed, but ink contamination and poor drying occur
Solution Approach 1:
The patent segments the full colour printing process into separate colour stations (Cyan, Magenta, Yellow, Black) that print simultaneously or in rapid sequence without requiring ink drying between stations. Each station deposits its ink directly onto the substrate without waiting for previous inks to dry, eliminating the ink trapping problem while maintaining full colour capability.
Solution Approach 2:
The patent employs preliminary halftoning and colour separation of the digital image before printing. The image is converted into halftoned separations for each colour channel, which are then printed simultaneously. This preliminary processing allows the system to use non-transparent inks without requiring ink trapping, as the halftoning pattern ensures proper colour reproduction without overprinting.
2Ease of manufacture
If ink trapping is used to create full colour images, then colour gamut is expanded, but excessive ink usage occurs
Solution Approach 1:
The patent divides the colour reproduction task into separate halftoned colour channels (CMYK) that are printed as distinct patterns on the substrate. Each colour is represented by a halftone pattern of dots rather than solid ink areas, and the colours are positioned in registration rather than overprinted. This segmentation allows full colour reproduction with reduced total ink coverage compared to traditional ink trapping methods.
Solution Approach 2:
The patent changes the fundamental parameter of ink transparency from transparent/semi-transparent to non-transparent opaque inks. This parameter change, combined with halftoning and simultaneous printing, allows the system to achieve full colour gamut without the need for ink trapping, thereby reducing total ink consumption since inks are not layered on top of each other.
3Ease of manufacture
If transparent inks are used for ink trapping, then secondary colours are created through overprinting, but ink contamination between stations occurs
Solution Approach 1:
The patent performs preliminary halftoning and colour separation to create distinct halftone patterns for each colour channel before printing. These pre-processed separations are then printed simultaneously or in rapid sequence with precise registration, eliminating the need for ink trapping. The halftoning process ensures that secondary colours are created through the optical mixing of halftone patterns rather than physical ink mixing, preventing contamination.
Solution Approach 2:
The patent uses halftone dot patterns as a copying mechanism to represent continuous tone images in each colour channel. Instead of using transparent inks that physically mix and trap, the system creates visual copies of the image in different colours through halftone patterns that are positioned in registration. This copying approach eliminates ink contamination while maintaining the ability to create secondary colours through optical mixing.
4Reliability
If ink drying time is required between printing stations, then ink trapping is achieved, but press operation speed is reduced
Solution Approach 1:
The patent segments the colour printing into separate halftoned channels that are printed simultaneously or in rapid succession without requiring drying time between stations. Each colour station deposits its halftoned ink directly onto the substrate without waiting for previous inks to dry, as the halftone pattern and precise registration eliminate the need for ink trapping. This segmentation enables high-speed press operation while maintaining colour quality.
Solution Approach 2:
The patent performs preliminary halftoning and colour separation before printing, which allows the subsequent printing process to proceed without ink drying delays. The pre-processed halftone separations are designed to be printed as distinct patterns that register precisely with each other, eliminating the need for ink trapping and enabling continuous high-speed operation across multiple printing stations.
Data Source
AI summary
The invention relates to a method of colour separation and printing full colour images, directly onto a substrate, in such a way that no ink trapping or the use of semi-transparent or transparent inks is required, and without requiring ink drying between ink stations. In particular, the method provides the steps of using non-transparent, semi-transparent, or transparent inks; half-toning (i.e. screening) separated CMYK digital image files to 1-bit files; creating additional ink colour channels from the 1-bit CMYK separated files; and performing removal of trapped or inked areas that will be overprinted, utilising the 1 bit files.