Inkjet Head Interlace Path Control for Banding Reduction

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Solution Overview

Problem

Inkjet printers using an interlace system with multiple nozzle heads in the sub-scanning direction face issues with unevenness in image recording due to ink discharge variations and movement errors, which can lead to banding and reduced printing speed when trying to prevent adjacent dots from forming during multiple scans.

Innovation Solution

The image recording device adjusts the number of paths (N) in the interlace system to ensure compatibility with high productivity and reduced unevenness by setting N = i × M, where M is the number of nozzle heads, allowing for optimal nozzle arrangement and discharge position shifting in both sub-scanning and main scanning directions to maintain high resolution and prevent banding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the number of nozzle heads is increased to improve printing speed, then productivity increases, but device complexity increases

Engineering Contradiction:
Improveprinting speedVSAvoidnumber of nozzle heads
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The inkjet head is divided into multiple nozzle heads (first nozzle head, second nozzle head, etc.) arranged in the sub-scanning direction. Each nozzle head contains multiple nozzles that discharge ink in the main scanning direction. This segmentation allows the system to achieve high printing speed by processing multiple lines simultaneously while managing complexity through modular organization of the nozzle heads.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If the interlace system is used to obtain high resolution, then manufacturing precision improves, but unevenness and banding occur due to ink discharge variations

Engineering Contradiction:
ImproveresolutionVSAvoidunevenness and banding
Core Design Contradiction:
Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The invention applies different discharge control strategies to different nozzle heads based on their local characteristics. The first nozzle head discharges ink at a first discharge position, while the second nozzle head discharges ink at a second discharge position that is shifted in the sub-scanning direction relative to the first discharge position. This local differentiation compensates for variations in ink discharge among nozzles, reducing banding and unevenness while maintaining high resolution through the interlace system.

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If the number of paths N is increased to improve resolution, then manufacturing precision improves, but productivity decreases due to increased scanning repetitions

Engineering Contradiction:
ImproveresolutionVSAvoidprinting speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

Instead of increasing the number of paths N in the main scanning direction to improve resolution, the invention shifts the discharge positions of multiple nozzle heads in the sub-scanning direction. This dimensional approach allows the system to achieve high resolution by utilizing the sub-scanning direction for position differentiation, thereby maintaining high printing speed without requiring excessive scanning repetitions.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP2255964B1Image recording device
Publication Date: 2019.12.18 SCREEN HOLDINGS CO LTD
  • EP2255964B1 patent drawingFigure 1
  • EP2255964B1 patent drawingFigure 2
  • EP2255964B1 patent drawingFigure 3

AI summary

Provided is an image recording device for recording an image (P) by an interlace method in which the number of paths is N and the image is recorded by scanning a specified region repeatedly for N times by using an inkjet head (10) with a structure in which four nozzle heads (10) are line up in a sub-scanning direction. The image recording device is provided with a storage unit for storing plural numbers N of paths such that N=i×M is satisfied when i is an integer of 1 or more and an input unit for selecting and inputting the number N of paths according to the required resolution.