Reflex Printing Temperature Feedback Control
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Solution Overview
Problem
Existing moving web printing systems face inaccuracies in image registration due to temperature-induced changes in roller diameters and web shrinkage, leading to misregistration of images printed by different printheads.
Innovation Solution
A method and system that identify temperature changes in rollers and web media, adjust web velocity computations, and modify printhead firing signals to account for these changes, using temperature sensors, encoders, and a controller to compute accurate web velocities and positions, thereby compensating for thermal expansion and shrinkage effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If temperature feedback control is implemented to compensate for thermal expansion and shrinkage, then image registration accuracy is improved, but device complexity increases due to additional temperature sensors and control mechanisms
Solution Approach 1:
The patent implements feedback control by measuring actual temperatures of rollers and web material with temperature sensors, comparing these measurements to desired temperature values, and adjusting heating element operation accordingly. This closed-loop feedback system compensates for thermal expansion and shrinkage in real-time, maintaining accurate image registration despite temperature variations during the printing process.
Solution Approach 2:
The system dynamically adjusts operational parameters including heating element power levels, web velocity computations, and printhead firing signals based on measured temperature changes. By changing these parameters in response to temperature feedback, the system compensates for thermal effects on roller diameters and web dimensions, resolving the contradiction between precision and complexity.
2Manufacturing precision
If web velocity computations are adjusted in real-time based on temperature changes, then registration accuracy is improved, but measurement precision requirements increase
Solution Approach 1:
Temperature sensors provide continuous feedback on roller and web material temperatures, which the control system uses to compute corrected web velocities. This feedback loop ensures that even small temperature variations are detected and compensated for through real-time velocity adjustments, maintaining registration accuracy while managing measurement precision requirements through practical sensor selection.
Solution Approach 2:
The control system acts as an intermediary that processes temperature measurements and translates them into corrected velocity computations and printhead firing signals. This intermediary layer buffers the relationship between temperature measurement precision and final registration accuracy, allowing the system to achieve high registration accuracy through computational correction rather than requiring extremely precise temperature measurements alone.
3Reliability
If multiple temperature sensors and correction mechanisms are added to compensate for thermal effects, then reliability of image registration is improved, but device complexity increases
Solution Approach 1:
The system employs feedback control where temperature sensors continuously monitor roller and web temperatures, and the control system automatically adjusts web velocity and printhead firing timing based on these measurements. This automated feedback mechanism improves registration reliability by compensating for thermal effects in real-time without requiring complex manual intervention or multiple redundant sensor systems.
Solution Approach 2:
The control system performs self-correction by automatically processing temperature measurements and adjusting operational parameters without external intervention. The system serves itself by detecting temperature deviations and independently computing the necessary corrections to web velocity and printhead firing signals, improving reliability while minimizing the need for additional complex control mechanisms.
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 approach enhances the accuracy of image registration by accurately adjusting web velocities and printhead firing signals, reducing misregistration and visual noise in printed images.
Implementation Method 1
temperature-induced changes in roller diameters and web shrinkage
Implementation Method 2
temperature-induced changes in roller diameters and web shrinkage
Implementation Method 3
Each of the rollers 22, 30, and 34 has an encoder mounted near the surface of the roller. These encoders may be mechanical or electronic devices that measure the angular velocity of a roller monitored by the encoder
Data Source
AI summary
A method for operating a web printing system enables web and roller changes arising from temperature changes to be identified and used to adjust operation of the reflex registration system. The method includes identifying a temperature change for at least one roller in a web printing system, identifying a temperature change for a web moving through the web printing system at one or more locations in the web printing system, modifying web velocity computations for a reflex registration system with reference to the identified temperature change for the at least one roller and the identified temperature change for the web, and operating printheads to eject ink onto the web at positions identified with reference to the modified web velocity computations.