Emulated Encoder Frequency Adjustment for Print Drift

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Solution Overview

Problem

Industrial print systems face inaccuracies in monitoring media speed, leading to cumulative dot placement errors and drift due to limitations in mechanical and digital systems, particularly when using emulated encoder frequencies in continuous printing processes.

Innovation Solution

A system and method for adjusting emulated encoder frequencies by determining the difference between an encoder count and a theoretical count, and adjusting the frequency of the emulated encoder signal to mitigate these differences, using a combination of hardware and software engines to calculate and generate the adjusted signal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If mechanical encoders and optical sensors are used to monitor media speed, then speed monitoring capability is provided, but measurement precision deteriorates leading to cumulative dot placement errors

Engineering Contradiction:
Improvemedia speed measurement precisionVSAvoiddot placement accuracy
Core Design Contradiction:
Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent replaces mechanical encoders with a digital mark-based speed monitoring system. Marks are printed on the media at known intervals and detected by sensors, allowing speed calculation through digital processing rather than mechanical encoding. This substitution eliminates the precision limitations of mechanical systems while maintaining speed monitoring capability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses optical copies (images) of physical marks on the media to determine media speed and position. Instead of directly measuring physical motion with mechanical sensors, the system captures optical images of marks and processes them digitally to calculate speed, thereby achieving higher precision without mechanical components.

Inventive Principle:
Principle #26Copying

2Productivity

If emulated encoder frequencies are used in continuous printing, then printing continuity is maintained, but drift accumulates over the course of the print job

Engineering Contradiction:
Improvecontinuous printing capabilityVSAvoiddot placement accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent implements a feedback mechanism where the actual media speed is continuously measured using the mark-based system and compared against the speed assumed by the emulated encoder. The system calculates drift between actual and expected positions and adjusts dot placement in real-time to compensate, thereby maintaining precision throughout continuous printing operations.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent performs preliminary calculations of drift and required compensation before executing dot placement. By pre-calculating the necessary adjustments based on measured media speed variations, the system proactively corrects for drift rather than reacting to errors after they occur, maintaining accuracy throughout the print job.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3213090B1Adjusting emulated encoder frequencies
Publication Date: 2020.06.17 HEWLETT PACKARD DEVELOPMENT COMPANY LP
  • EP3213090B1 patent drawingFigure 1~2
  • EP3213090B1 patent drawingFigure 3
  • EP3213090B1 patent drawingFigure 4

AI summary

Adjusting emulated encoder frequencies in an example embodiment can include determining a difference between an encoder count and a theoretical encoder count and adjusting a frequency of an emulated encoder signal to mitigate at least some of the difference between the encoder count and the theoretical encoder count.