Printhead Alignment via Web Lateral Shift Detection

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Solution Overview

Problem

High-speed continuous-forms printing systems face challenges in maintaining precise printhead alignment due to fluctuations in the web's physical properties, leading to lateral shifts and reduced print quality, as existing solutions fail to dynamically adjust for micron-level variations during printing.

Innovation Solution

A system comprising a sensor and controller that detects lateral shifts in the web and adjusts the printhead position in real-time to compensate for these changes, using a positioning device and implementing filters to prevent overshooting and noise responses, ensuring accurate marking across multiple color planes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If steering systems are calibrated to align the web laterally, then initial web alignment is improved, but lateral shifts during printing occur due to web property fluctuations

Engineering Contradiction:
Improveweb alignmentVSAvoidalignment stability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies dynamics by making the printhead position adjustable during operation. The system transitions from a static aligned position to a dynamically adjustable position that can be modified in real-time based on detected web lateral shifts, allowing the printhead to track and compensate for web movement throughout the printing process

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements feedback through a sensor that continuously detects the lateral position of the web and provides this information to the controller. The controller then adjusts the printhead position based on this feedback signal, creating a closed-loop control system that maintains alignment despite web property fluctuations

Inventive Principle:
Principle #23Feedback

2Manufacturing precision

If printhead position is adjusted dynamically to compensate for web shifts, then print quality is improved, but system complexity increases

Engineering Contradiction:
Improveprinthead positioning accuracyVSAvoidalignment system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary controller that mediates between the web position sensor and the printhead positioning mechanism. This controller processes the sensor signals and generates appropriate adjustment commands, simplifying the overall system architecture while enabling dynamic compensation for web lateral shifts

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If filters are applied to prevent overshooting and noise responses, then positioning stability is improved, but response time increases

Engineering Contradiction:
Improvepositioning stabilityVSAvoidadjustment response time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies parameter changes by adjusting filter characteristics based on operating conditions. The system modifies filter parameters dynamically to optimize the balance between smoothing noise/preventing overshoot and maintaining adequate response speed, allowing stable positioning without excessive delay

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2857208B1Alignment of printheads in printing systems
Publication Date: 2019.10.30 RICOH CO LTD
  • EP2857208B1 patent drawingFigure 1
  • EP2857208B1 patent drawingFigure 2
  • EP2857208B1 patent drawingFigure 3

AI summary

Systems and methods are provided for aligning printheads of a printing system (400). The system comprises a sensor (430) and a controller (420). The sensor is able to detect changes in a lateral position of a web of print media traveling through a continuous-forms printing system, and the controller is able to adjust a lateral position of a printhead while the printing system is operating to compensate for the detected changes in web position.