Skew Correction in Image Reading Apparatus

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Solution Overview

Problem

Image reading apparatuses face challenges in efficiently correcting skew defects in original images due to variations in roller alignment, leading to incomplete readings and poor operability, as existing solutions either rely on limited image processing corrections or mechanical skew correction methods that introduce noise and require multiple user operations.

Innovation Solution

An image reading apparatus with a controller that dynamically switches between mechanical skew correction and image processing tilt correction based on detected skew amounts, stopping conveyance when excessive skew is detected and using image processing for tilt correction within predetermined threshold values to prevent image defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If mechanical skew correction is used to correct considerable skew, then the tilt correction capability is improved, but collision noise and driving noise are produced

Engineering Contradiction:

Improveskew correction capabilityVSAvoidnoise

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent replaces mechanical skew correction with image processing-based tilt correction. The controller detects skew amounts from read images and applies digital correction algorithms to eliminate tilt, avoiding the collision noise and driving noise inherent in mechanical correction systems while maintaining effective skew correction capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates a digital copy of the original image through reading, then performs skew correction on this copy using image processing. This allows correction of considerable skew without physical contact or mechanical intervention, eliminating noise generation while preserving the original document

Inventive Principle:

Principle #26Copying

2Manufacturing precision

If mechanical skew correction is used for originals with abrupt skew, then the tilt correction is effective, but the reading processing must be temporarily finished and restarted

Engineering Contradiction:

Improveskew correction effectivenessVSAvoidreading processing continuity

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent enables continuous reading processing by performing tilt correction through image processing for each original without temporarily finishing and restarting operations. The controller continuously detects skew amounts and applies correction algorithms, maintaining uninterrupted reading flow even when dealing with originals having abrupt skew variations

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

By replacing mechanical skew correction with image processing, the system eliminates the need to temporarily finish reading processing. The digital correction method allows seamless, continuous operation as it doesn't require physical intervention or restart procedures

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Object-generated harmful factors

If image processing tilt correction is used, then noise is reduced, but the correction is limited and cannot handle considerable skew

Engineering Contradiction:

Improvenoise reductionVSAvoidskew correction range

Core Design Contradiction:

Object-generated harmful factorsVSManufacturing precision

Solution Approach 1:

The patent enhances the skew correction range by dynamically adjusting image processing parameters based on detected skew amounts. The controller modifies correction algorithms to handle various degrees of skew, from minor to considerable, expanding the effective correction range beyond traditional image processing limitations while maintaining noise reduction benefits

Inventive Principle:

Principle #35Parameter changes

4Manufacturing precision

If the reading processing is forcedly finished when skew exceeds limit, then the tilt correction limit is respected, but multiple user operations are required and usability deteriorates

Engineering Contradiction:

Improveskew correction accuracyVSAvoiduser operation frequency

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The patent replaces mechanical skew correction with image processing, allowing the system to handle a broader range of skew amounts without forcing reading processing to end. This eliminates the need for users to repeatedly set originals, improving ease of operation while maintaining accurate tilt correction through continuous image-based correction

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS10110776B2Image reading apparatus and image reading method

Publication Date: 2018.10.23 CANON KK

AI summary

An image reading apparatus reads an original image of an original placed on an original tray by a scanner unit. The original is conveyed to a reading position used by the scanner unit from the original tray through a conveyance path. A registration roller pair configured to mechanically correct skew of the original at a time of conveyance of the original is provided on the conveyance path. The image reading apparatus calculates a skew amount at the time of the conveyance of the original based on the original image, and conducts image processing on the original image based on the skew amount, to thereby correct a tilt of the original image. The image reading apparatus stops the conveyance of the original when the absolute value of the skew amount is larger than a first threshold value.