Web Speed Adaptive Image Capture for Label Verification
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Solution Overview
Problem
In-printer compliance testing for symbols printed on media is inaccurate due to non-linear motion of the web medium, leading to distorted verification images and unreliable real-time print quality adjustments.
Innovation Solution
A method and system that monitor and adjust the speed of the web medium during printing, predicting and compensating for distortions in the captured images based on the monitored speed, ensuring accurate compliance testing and quality control before printed items emerge from the printer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If in-printer compliance testing is performed using captured images of nascent labels, then verification of label accuracy can be performed prior to emergence from the printer, but the non-linear motion of the web medium causes image distortion and reduces measurement precision
Solution Approach 1:
The system captures images of the printed symbol during the print process, compares the captured image to the intended print data, and uses this feedback to detect printing errors in real-time. The feedback loop includes capturing the symbol image, comparing it to print command data, identifying discrepancies, and generating error signals for correction.
Solution Approach 2:
The system dynamically adjusts the sampling rate and image capture timing based on the actual speed of the web medium. By monitoring web speed and modifying capture parameters accordingly, the system compensates for non-linear motion effects and maintains measurement precision despite varying print speeds.
2Measurement precision
If the web medium motion is monitored and image capture rate is adjusted in real-time, then measurement precision can be maintained despite non-linear motion, but device complexity increases due to additional sensors and control mechanisms
Solution Approach 1:
The web speed sensor serves multiple functions: it monitors the speed of the web medium for timing synchronization, provides feedback for adjusting image capture rates, and enables compensation for non-linear motion effects. This multi-functionality reduces the need for separate dedicated components for each function.
Solution Approach 2:
The system uses the existing motion of the web medium itself to trigger the image capture process. The web's own movement provides the timing signal for when to capture images at specific positions, eliminating the need for external triggering mechanisms and reducing overall system complexity.
3Device complexity
If images are captured at fixed intervals regardless of web speed variations, then device complexity is minimized, but manufacturing precision deteriorates due to distorted verification images during non-linear motion
Solution Approach 1:
The system transitions from static fixed-interval image capture to dynamic speed-adaptive capture. The image capture rate and timing are dynamically adjusted based on real-time web speed measurements, allowing the system to maintain verification precision during accelerating and decelerating phases of web motion.
Solution Approach 2:
The system performs preliminary speed measurement and uses this information to pre-calculate optimal image capture timing and sampling rates before actual verification begins. This preliminary action ensures that images are captured at the correct moments even during rapid speed changes.
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 method and system provide accurate compliance testing and real-time quality control by adjusting image capture rates and applying corrective changes to maintain image quality despite non-linear motion, enhancing the reliability of printed symbols.
Implementation Method 1
As the heat sensitive web medium is drawn into proximity with the thermal printhead, portions of its surface are marked controllably by selective heating therewith. The appearance of the surface portions may thus be darkened from a light shade (e.g., white or near-white) to print the markings.
Data Source
AI summary
Printing symbols on media is described. Sequential parts of a symbol are marked onto each of multiple corresponding sequential segments of the medium. A characteristic of each of the sequential symbol parts is evaluated. A speed is monitored with which the medium is moved upon the marking of each of the sequential symbol parts onto each of the corresponding sequential segments of the medium. An image, captured in relation to the evaluation, is adjusted based on the monitored speed. Adjusting the captured image may include setting a rate at which the evaluation of the characteristic of each of the sequential symbol parts is performed based on the monitored speed or alternatively, predicting a distortion in the evaluated characteristic of each of the sequential symbol parts corresponding to the monitored speed, and applying a change to the captured image corresponding to, and ameliorating the predicted distortion.