Print Media Size Variation Detection Using Integrated Imaging
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Solution Overview
Problem
Commercial inkjet printing systems face challenges in detecting and compensating for unanticipated stretch or shrink in print media, leading to color correlation loss and blurry content due to the limited capability of existing high-speed cameras to monitor size variations across the entire print media.
Innovation Solution
A printing system with integrated imaging systems positioned opposite the print media, capturing images of test patterns with varying mark numbers in the in-track direction, analyzing these images to detect size variations, and adjusting printing operations based on calculated compensation values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high-speed cameras are used to detect size variations in print media, then detection speed is improved, but the ability to monitor the entire print media is limited
Solution Approach 1:
The imaging system divides the print media into multiple scan lines that are captured simultaneously by the camera sensor. Each scan line represents a cross-section of the print media, and by processing multiple scan lines, the entire media width is monitored without requiring physical movement of the camera.
Solution Approach 2:
The system uses periodic triggering of the camera at high speed to capture multiple images of the moving print media. Each trigger corresponds to a specific position, allowing the system to build up a complete picture of the entire media width through sequential high-speed captures.
2Area of stationary object
If multiple cameras are mounted to monitor all patterns, then monitoring coverage is improved, but system cost increases
Solution Approach 1:
A single camera is designed to perform multiple functions: it captures test patterns for size variation detection, monitors production quality, and can track positional information. The camera serves as a multi-functional device that replaces what would traditionally require multiple specialized cameras.
Solution Approach 2:
The imaging system uses the existing test patterns printed on the media itself as the detection target, eliminating the need for separate markers or additional components. The test patterns serve dual purposes: they are part of the printed content and simultaneously function as measurement references.
3Measurement precision
If visible patterns are printed on the print media for detection, then size variation detection is enabled, but the patterns occupy valuable print space and must be trimmed
Solution Approach 1:
Instead of using physical test patterns that occupy space, the system creates a digital copy or representation of the media surface by capturing images with the camera. The test patterns are captured optically and processed digitally to extract size variation information without requiring physical presence of large markers.
Solution Approach 2:
The system changes the scale and density of test patterns to make them imperceptible to humans while remaining detectable by the camera. By reducing the pattern size to a level where they appear as uniform texture rather than distinct shapes, the media maintains full visual quality while enabling precise measurement through optical detection of the fine pattern structure.
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 solution enables simultaneous and accurate detection of size variations across the print media, allowing for real-time adjustments to maintain color correlation and image quality, thereby preventing blurry content and hue degradation.
Implementation Method 1
an opening in the housing for receiving light reflected from the print media
Implementation Method 2
a folded optical assembly in the housing that receives the reflected light and transmits the light a predetermined distance
Data Source
AI summary
A printing system includes a print media having two sets of test patterns formed or printed in at least two margins adjacent a content area on the print media. The two sets of test patterns are separated by a pattern distance and at least two test patterns in each set of test patterns have a different number of marks. Two integrated imaging systems are disposed opposite the print media and are mechanically tied together and separated by a fixed distance. The integrated imaging systems substantially simultaneously capture images of the two sets of test patterns. An image processing device can process the images to determine if one or more size variations have occurred in the print media in the in-track direction.