Inkjet Dot Size Control for Density Compensation

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Solution Overview

Problem

Existing dot-based printing systems, particularly inkjet printers, face inefficiencies in correcting color density fluctuations due to nozzle variations, requiring time-consuming processes that involve creating new raster images for every density correction.

Innovation Solution

A method using a control unit that modifies color density values after a raster image is created, adjusting the number and size of print dots to achieve pre-defined density values without requiring new raster image creation, allowing for quick and flexible correction of brightness differences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If color density correction is performed by creating a new raster image before printing, then color density accuracy is improved, but printing productivity deteriorates due to time-consuming raster image creation

Engineering Contradiction:

Improvecolor density accuracyVSAvoidprinting speed

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The system performs preliminary characterization of each nozzle's drop volume during manufacturing or setup, storing this data for later use. This preliminary action allows the system to compensate for nozzle variations during normal printing without requiring time-consuming raster image recreation, thus resolving the contradiction between accuracy and speed

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes the parameter of drop volume for each nozzle based on stored characterization data, adjusting the number of drops or drop size to compensate for manufacturing variations. This parameter adjustment enables accurate color density correction without regenerating raster images, maintaining both precision and productivity

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If density correction coefficients are stored and applied before raster image creation, then color density uniformity is improved, but device complexity increases due to additional correction units and processing steps

Engineering Contradiction:

Improvecolor density uniformityVSAvoidsystem complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The system extracts the density correction function from the main printing pipeline and implements it as a simple scaling operation applied to existing raster image data. By separating the correction step from raster image creation, the system achieves color density uniformity without adding complex correction units or processing steps

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The system uses existing raster image data as a template and applies scaling factors to adjust drop counts, rather than creating entirely new corrected images. This copying approach maintains color density uniformity while avoiding the complexity of multiple correction units and processing pipelines

Inventive Principle:

Principle #26Copying

Data Source

PatentUS10596808B2Method for density compensation by drop size adaptation

Publication Date: 2020.03.24 HEIDELBERGER DRUCKMASCHINEN AG

AI summary

A method for modifying color density values in a dot-based printing system uses a control unit. The control unit implements the modification of the color density values after a raster image has been created and modifies the number and/or size of print dots to be applied to a printing substrate in order to attain pre-defined color density target values.