Duplex Print Inspection Roller Layout for Accurate Optical Sensing

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Solution Overview

Problem

Existing image inspection techniques for duplex printing apparatuses face challenges in achieving high inspection accuracy while minimizing apparatus footprint, particularly when using two optical detectors, and often result in measurement errors due to varying distances and potential interference between colorimeters.

Innovation Solution

The apparatus employs a configuration with four transport rollers arranged in a horizontal direction, allowing overlapping transport paths for the print medium, with inspection parts on opposite sides to maintain consistent distance and reduce footprint, ensuring accurate inspection of both surfaces without interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If colorimeters are arranged to interpose the print medium therebetween from a vertical direction, then both surfaces can be inspected, but measurement accuracy deteriorates due to distance change and mutual interference between colorimeters

Engineering Contradiction:

Improveability to inspect both surfacesVSAvoidinspection accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent transitions from vertical arrangement (Patent Literature 2) to horizontal arrangement of colorimeters on the same side as the print medium. This dimensional change eliminates the distance variation problem and mutual interference issues while maintaining the ability to inspect both surfaces through coordinated operation of multiple colorimeters.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent introduces a light shield as an intermediary element between colorimeters and the print medium. This light shield prevents illumination light from one colorimeter from entering the detector of another colorimeter, thereby eliminating mutual interference while allowing both surfaces to be inspected.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If inspection units are arranged from respective sides with the print medium between them, then both surfaces can be inspected, but apparatus footprint increases

Engineering Contradiction:

Improveability to inspect both surfacesVSAvoidapparatus footprint

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent merges the inspection function for both surfaces into a single horizontal arrangement of colorimeters on one side. By coordinating multiple colorimeters in this consolidated arrangement, the system can inspect both surfaces without requiring separate inspection units from opposite sides, thereby reducing the apparatus footprint.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of operation

If the print medium is not backed up by a roller during inspection, then inspection can be performed, but inspection accuracy reduces due to measurement error from distance change

Engineering Contradiction:

Improveinspection capabilityVSAvoidinspection accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent introduces a light shield as an intermediary element that serves dual purposes: it prevents mutual interference between colorimeters and simultaneously maintains a constant distance between the colorimeter and the print medium surface. This constant distance ensures measurement accuracy while allowing the inspection to proceed.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 configuration enables high-accuracy image inspection on both surfaces of a print medium while keeping the apparatus footprint small, by maintaining consistent distance and reducing interference between optical units.

Implementation Method 1

a first transport roller and a second transport roller arranged at positions differing from one another in a horizontal direction, and each transporting the print medium in a first transport direction having a horizontal component while wound with the print medium in such a manner as to contact the second recording surface

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

a first inspection part configured to optically inspect a first region of a first recording surface wound on the first transport roller

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS20260027843A1Image inspection apparatus, image inspection method and printing apparatus

Publication Date: 2026.01.29 SCREEN HOLDINGS CO LTD

AI summary

An image inspection apparatus and a printing apparatus according to present invention transport a print medium stretched over first to fourth rollers and inspect optically a first region of the first recording surface wound on the first transport roller by a first inspection part and a second region of the first recording surface wound on the second transport roller by a second inspection part. Further, a third region of the second recording surface wound on the third transport roller is inspected optically by a third inspection part and a fourth region of the second recording surface wound on the fourth transport roller is inspected optically by a fourth inspection part. In a top view, the print medium transported between the first transport roller and the second transport roller and the print medium transported between the third transport roller and the fourth transport roller overlap each other at least partially.