UV-Curing Inkjet Printer Multi-Pass Hardening
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Solution Overview
Problem
Inkjet printers using ultraviolet curing ink face challenges in preventing intercolor bleeding and uneven dot shapes due to increased dot density and reduced distance between ink dots, leading to decreased print quality, especially at high printing rates.
Innovation Solution
A printing apparatus with a multi-pass mode configuration that includes N-number of inkjet heads, temporarily hardening light sources for partial hardening of ink dots with lower intensity UV light, and a fully hardening light source for complete hardening, along with a pixel selector to manage ink dot formation and spacing, reducing the number of colors per pass and varying spatial frequencies for each printing pass to minimize dot contact and bleeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the density of ink dots is increased to improve print resolution, then print resolution is improved, but intercolor bleeding occurs due to dot contact
Solution Approach 1:
The patent applies preliminary action by irradiating ultraviolet light onto ink dots immediately after ejection in each main scan operation. This pre-hardening prevents liquid ink dots from contacting each other before they can spread and mix, thereby preventing intercolor bleeding while maintaining high dot density for improved print resolution.
Solution Approach 2:
The patent uses periodic action by performing multiple main scan operations with intermittent ultraviolet irradiation. Each main scan operation is followed by UV irradiation to harden the deposited ink dots, creating a cyclic process that progressively builds up the print image while preventing dot contact and bleeding throughout the printing sequence.
2Object-generated harmful factors
If ultraviolet light is radiated to harden ink dots and prevent bleeding, then intercolor bleeding is prevented, but ink dot shapes become uneven due to repulsion from surrounding hardened dots
Solution Approach 1:
The patent applies partial action by performing ultraviolet irradiation repeatedly in each main scan operation rather than using a single intense irradiation. This gradual hardening approach allows ink dots to be hardened incrementally, reducing the repulsion effect from fully hardened surrounding dots and maintaining more uniform ink dot shapes while still preventing intercolor bleeding.
3Object-generated harmful factors
If printing is performed in multi-pass mode to increase distance between ink dots, then intercolor bleeding is reduced, but printing speed decreases
Solution Approach 1:
The patent merges the functions of ink deposition and hardening into a single integrated process. By combining the ink ejection and UV irradiation functions in one main scan operation, the system achieves effective bleeding prevention without requiring multiple separate printing passes, thereby maintaining high printing speed while preventing intercolor bleeding.
4Productivity
If the number of printing passes is reduced to maintain printing speed, then printing speed is maintained, but dot contact and bleeding occur due to high dot density
Solution Approach 1:
The patent applies preliminary action by hardening ink dots immediately after ejection in each main scan operation. This immediate UV irradiation creates a protective hardened state that prevents dot contact and bleeding, allowing the system to maintain high dot density and printing speed without requiring multiple printing passes.
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 effectively prevents intercolor bleeding and ensures uniform ink dot shapes, enhancing print quality by controlling the viscosity and hardening state of ink dots, allowing for high-quality printing with reduced printing passes and maintaining printing speed.
Implementation Method 1
temporarily hardening light sources that radiate ultraviolet light which hardens ultraviolet curing ink on the medium to a temporarily hardened state
Implementation Method 2
fully hardening light source that radiate ultraviolet light which completes hardening of the ultraviolet curing ink on the medium
Data Source
AI summary
The disclosure appropriately performs high-quality printing in a case of using ultraviolet curing ink in a serial type inkjet printer. As a solution, a printing apparatus for performing printing in an inkjet mode by a multi-pass scheme includes: inkjet heads, a temporarily hardening light source, a fully hardening light source, and a controller configured to serve as a pixel selector, wherein the temporarily hardening light source radiates ultraviolet light whenever a predetermined number of main scan operations are performed, and the fully hardening light source radiates ultraviolet light after main scan operations of all printing passes finish.