Circular Measuring Marks for Automated Register Measurement
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Solution Overview
Problem
Existing methods for automated alignment and register measurement in printing presses require separate register sensors and test patterns that cover entire sheets, leading to increased paper waste and reduced productivity, and often link register offset evaluation with color control, which is not optimal for high-quality demands.
Innovation Solution
A method using circular measuring marks integrated into color control strips, allowing for automated alignment and register measurement by a computer, which evaluates the center position of these marks with subpixel accuracy, eliminating the need for separate register sensors and extensive test patterns, and enabling simultaneous color measurement and alignment correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate register sensors and test patterns covering entire sheets are used, then automated alignment and register measurement can be performed, but paper waste increases and productivity decreases
Solution Approach 1:
The invention divides the traditional full-sheet test pattern into multiple smaller circular measuring marks distributed across the sheet. Each circular mark contains alignment information for a specific printing unit, allowing selective measurement without requiring complete sheet coverage by test patterns.
Solution Approach 2:
The circular measuring marks serve multiple functions: they enable alignment measurement, register measurement, and can be integrated with color control strips. This multi-functionality eliminates the need for separate dedicated test patterns and sensors for different measurement types.
2Measurement precision
If separate register sensors are used, then automated register measurement is achieved, but device complexity and cost increase
Solution Approach 1:
The invention enables existing image sensors used for quality control to perform both quality inspection and register/alignment measurement functions. This eliminates the need for separate dedicated register sensors, reducing device complexity and cost while maintaining measurement capability.
Solution Approach 2:
The invention combines the functions of quality control imaging and register measurement into a single integrated system. The same image sensor and processing software that perform quality control also extract alignment and register information from the circular measuring marks.
3Measurement precision
If image sensors with sufficiently high resolution are used for color control, then they can evaluate register marks, but the requirement for high resolution increases system demands
Solution Approach 1:
The invention changes the parameters of the measuring marks (using larger circular formats with specific geometric features) to make them evaluable by existing image sensors without requiring extreme resolution increases. The circular design with identifiable features allows accurate center determination even at moderate resolutions.
Data Source
AI summary
A method for automated alignment and register measurement in a printing press provides for test patterns having multiple color separations to be printed by the printing press on a printing substrate, recorded by using at least one image sensor of an image acquisition system as a digital overall image, evaluated by a computer with respect to an alignment/register offset and then corrected by the computer for the alignment/register offset. Circular measuring marks having known diameter for each color separation are integrated into the test patterns and the computer ascertains the center position of each circular measuring mark with subpixel accuracy and thus computes the alignment/register offset by cutting out an image region having at least one circular measuring mark from the digital overall image and determining parameters of a model of a printing point of the circular measuring mark from the digital overall image.