Printing Device Dot Group Positioning for Image Quality
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Solution Overview
Problem
In image forming technologies that combine dots formed by different main scanning, shifts in dot formation positions lead to reduced image quality, particularly affecting gradation values and color tone, due to errors in bi-directional printing and multipass printing methods, as well as issues like buckling of printing media.
Innovation Solution
A printing device that divides dot formation into first and second pixel groups, with a print head capable of forming multiple color dots at high resolution, where the relative position between these groups is adjusted to maintain color differences within specific ranges in the CIEL*a*b* color space, ensuring minimal changes in brightness and color tone even with dot position shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If bi-directional printing or multipass printing is used to improve printing speed, then productivity is improved, but shifts in dot formation positions occur leading to reduced image quality
Solution Approach 1:
The pixel groups are divided into first and second pixel groups based on their positional relationships. By segmenting the processing into different pixel groups with specific spatial arrangements, the patent enables controlled dot formation that compensates for shifts occurring during bi-directional or multipass printing, thus maintaining image quality while achieving high printing speed
Solution Approach 2:
The patent controls the relative positions between first and second pixel groups within specific parameter ranges (e.g., horizontal distance 0.2-0.5 inches, vertical distance 0-0.1 inches). By changing and controlling these positional parameters, the invention ensures that dot formation shifts do not degrade image quality, allowing high-speed printing methods to be used effectively
2Manufacturing precision
If dot formation positions are adjusted to maintain image quality, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent pre-establishes the spatial relationship rules between first and second pixel groups before actual printing occurs. By defining acceptable relative position ranges in advance and organizing pixels into predetermined groups, the system simplifies the printing process rather than adding complexity, as the grouping logic is applied automatically during normal operation
Solution Approach 2:
The patent creates a flexible printing system where pixel groups can be dynamically assigned to first or second groups based on their relative positions. This dynamic grouping approach allows the system to adapt to different printing conditions and maintain image quality without requiring complex mechanical adjustments or additional hardware components
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
The solution effectively suppresses changes in brightness and color tone by maintaining color differences within predetermined ranges, even when dot formation positions shift, thereby improving image quality and consistency across various printing conditions.
Implementation Method 1
it is well known as a method of using a deformation of a piezo-element caused by increasing voltage
Implementation Method 2
a method of using foam (bubbles) generated by heating the ink
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
A printing device includes the following features. The first dot group in which dots are formed based on the first printing condition and the second dot group in which dots are formed based on a printing condition which is different from the first printing condition are formed together in a common region. In the common region, when the printing is performed in a plurality of conditions such that a difference of the dot pitch between a formation position of dots belonging to the first pixel group and a formation position of dots belonging to the second pixel group is 2/720 inch to 5/720 inch, the change in CIEL*a*b* of the printed image is within the preliminary determined range.