Estimating Pen to Paper Spacing via Optical Alignment Scanning

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Solution Overview

Problem

Developing and producing tools to directly measure pen to paper spacing (PPS) in inkjet printing devices is costly and inefficient, affecting print quality.

Innovation Solution

An inkjet printing device estimates PPS using an optical scanning procedure on an alignment pattern printed by the device, determining the dynamic swath height error effect to calculate PPS without additional hardware, enabling automated and cost-effective measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If direct measurement tools are used to measure pen to paper spacing, then measurement precision is improved, but device complexity and cost increase

Engineering Contradiction:
ImprovePPS measurement precisionVSAvoidmeasurement tool complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses an optical scanner to create a digital copy/image of the alignment pattern printed on the medium. By scanning the printed alignment pattern and analyzing the scanned image, the system determines PPS without requiring direct physical measurement tools. The alignment pattern serves as a copy that encodes PPS information, which can be extracted through image processing algorithms.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent replaces mechanical measurement tools with an optical scanning system. Instead of using physical calipers or micrometers to measure the distance between printhead nozzles and medium, the system uses optical scanning to detect the alignment pattern and calculates PPS through software analysis of the scanned image data.

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

2Measurement precision

If direct measurement tools are used to measure pen to paper spacing, then measurement precision is improved, but manufacturing cost increases

Engineering Contradiction:
ImprovePPS measurement precisionVSAvoidmeasurement tool cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent uses an optical scanner to create a digital copy of the alignment pattern. This copying approach eliminates the need for expensive direct measurement hardware, as the scanner and image processing software provide sufficient measurement capability at lower cost.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The printing device uses its own existing components (printhead, optical scanner, processor) to perform the measurement function. The alignment pattern is printed by the device itself, and the same device's optical scanner analyzes the pattern to determine PPS, making the system self-sufficient and eliminating external measurement tool requirements.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If additional hardware is added to measure PPS, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
ImprovePPS measurement precisionVSAvoidhardware complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The optical scanner in the printing device is used for dual purposes: quality control/scanning operations and PPS measurement. By making the scanner serve multiple functions, the system avoids adding dedicated measurement hardware while maintaining measurement capability through the alignment pattern analysis method.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The printing device performs self-diagnosis and self-measurement using its existing components. The device prints the alignment pattern and then uses its own optical scanner and processor to analyze the pattern and determine PPS, eliminating the need for external measurement equipment.

Inventive Principle:
Principle #25Self-service

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 method allows for accurate estimation of PPS within a desired range, improving print quality without the need for separate measurement tools or additional hardware, thus reducing costs and enhancing operational efficiency.

Implementation Method 1

perform an optical scanning procedure on the printed alignment pattern to determine respective values of cross-media misalignment

Methodology Applied
Scientific EffectOptical scanning:

Data Source

PatentEP3233505B1Estimation of pen to paper spacing
Publication Date: 2019.11.13 HEWLETT PACKARD DEVELOPMENT COMPANY LP
  • EP3233505B1 patent drawingFigure 1~2A
  • EP3233505B1 patent drawingFigure 2B~2C
  • EP3233505B1 patent drawingFigure 2D

AI summary

Examples include estimation of pen to paper spacing (PPS). Examples include an alignment pattern printed on a medium at a target speed, an optical scan procedure performed on the printed alignment pattern to determine values of cross-media misalignment for first and second portions of the alignment pattern, determination of a dynamic swath height error (DSHE) effect value based on the values of cross-media misalignment, and estimation of an amount of PPS based on the determined DSHE effect value and the target print speed.