Foreign Object Position Detection in Image Scanners

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Solution Overview

Problem

Existing image reading apparatuses face challenges in accurately determining the position of foreign objects, such as dust or paper powder, which cause vertical stripe noise in document images, especially when they are attached to the image capturing device or a reference plate, making it difficult to correct the document image effectively.

Innovation Solution

The apparatus captures two images of a reference member under different light quantities and compares the gradation values to determine if a foreign object is on the image capturing device side or the reference member side, using a light source to illuminate the reference member with varying light quantities and analyzing the absolute difference in gradation values to accurately position the foreign object.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a captured image of a plain reference plate is used to determine foreign object appearance, then measurement precision is improved, but difficulty of detecting and measuring increases

Engineering Contradiction:

Improveforeign object detection accuracyVSAvoidforeign object position determination difficulty

Core Design Contradiction:

Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The system captures a reference image of the reference plate before document scanning to establish a baseline state. This preliminary action enables comparison with subsequent document images to detect foreign objects that may appear during scanning, improving detection accuracy while providing a reference for position determination.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system varies illumination parameters by capturing images under different light conditions (different light quantities). By comparing images taken with different illumination levels, the system can distinguish between foreign objects on the image capturing device versus those on the reference plate, resolving the position determination difficulty.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If multiple images under different light quantities are captured and compared, then foreign object position determination accuracy is improved, but use of energy increases

Engineering Contradiction:

Improveforeign object position determination accuracyVSAvoidenergy consumption for multiple image captures

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The system captures images under different light quantities only when foreign object detection is needed, rather than continuously. By performing the additional image capture selectively based on detection requirements, the system achieves accurate position determination while minimizing unnecessary energy consumption from redundant imaging operations.

Inventive Principle:

Principle #16Partial or excessive action

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 precise determination of the foreign object's position, enabling appropriate image correction and suppression of vertical stripe noise in document images by distinguishing between objects on the device and reference plate sides.

Implementation Method 1

a light source for emitting light to the reference member... a first image which is an image of the reference member captured under illumination of light with a first light quantity from the light source, and a second image which is an image of the reference member captured under illumination of light with a second light quantity

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS9860394B2Image reading apparatus, control method, and computer-readable, non-transitory medium

Publication Date: 2018.01.02 PFU LTD

AI summary

An image reading apparatus includes an image capturing module, a reference member, a light source for emitting light to the reference member, a foreign object determining module for determining whether or not a foreign object appears in a specific image, and a position determining module for determining whether the foreign object exists on the image capturing module side or on the reference member side, based on an absolute value of a difference between a gradation value in a region included in two images and corresponding to a region where the foreign object appears when the foreign object appears in the specific image. One image is an image of the reference member captured under illumination of light with a first light quantity from the light source, and other image is an image of the reference member captured under illumination of light with a second light quantity from the light source.