Scanner Glass Foreign Body Detection Using Multi-Sensor Focal Depth
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Solution Overview
Problem
Existing image reading devices with on-board automatic document feeders struggle to accurately detect foreign bodies like lint, dust, or dirt on the scanner glass platen, leading to linear noise areas in scanned images, as previous techniques fail to distinguish between document noise and foreign body noise with high accuracy, especially when the foreign body is larger than the CCD sensor interval or hides across all color channels.
Innovation Solution
The implementation of a system with multiple CCD photo-sensors arranged in the main scanning direction, which scan the same area from different angles, allowing for image superimposition and focal depth matching calculations to identify and correct noise caused by foreign bodies on the scanner glass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If one photo-sensor is used to read document images, then device complexity is reduced, but foreign body detection accuracy deteriorates
Solution Approach 1:
The patent divides the detection function into multiple photo-sensors (first and second photo-sensors) positioned at different locations. Each photo-sensor captures images from its specific position, and the control unit segments the analysis by comparing images from both sensors to detect foreign bodies. This segmentation allows accurate detection while maintaining reasonable device complexity through modular functionality.
2Measurement precision
If CCD photo-sensors are arranged at intervals in main scanning direction, then foreign body detection capability is improved, but device complexity increases
Solution Approach 1:
The patent makes the multiple photo-sensors perform the same basic function of capturing document images, but utilizes their different positions to achieve additional foreign body detection functionality. The control unit processes images from both sensors using the same image processing techniques, making the system multi-functional without requiring completely different detection mechanisms. This universality improves detection capability while controlling complexity through consistent processing methods.
3Measurement precision
If image superimposition and focal depth matching are performed, then noise correction accuracy is improved, but processing time increases
Solution Approach 1:
The patent performs image superimposition and focal depth matching as preliminary processing steps before final noise correction. The control unit first superimposes images from both photo-sensors, then calculates focal depth relationships, and only after these preliminary actions are complete does it proceed to noise correction. This preliminary action approach ensures high noise correction accuracy while managing processing time through structured sequential operations.
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 approach enhances the accuracy of foreign body detection and noise correction, ensuring improved imaging performance by distinguishing between document noise and foreign body noise, even when the foreign body is large or hides across all color channels.
Implementation Method 1
a plurality of CCD photo-sensors being arranged at intervals in a main scanning direction, the CCD photo-sensors being configured to read an image on a sheet of document conveyed in a sub-scanning direction
Data Source
AI summary
An image reading device includes: a scanner glass; photo-sensors arranged at intervals in a main scanning direction to read a document conveyed in a sub-scanning direction; an adjuster that adjusts the size of an overlapping area between a first and second image obtained by neighboring photo-sensors, the overlapping area constituting a first area of the first image and a second area of the second image; a superimposing portion that shifts either one of images of the first and second area to the other one; a judgment portion that judges whether the images having different focal depths exist based on the degree of matching between the first and second area; and a detector that detects a foreign body on the scanner glass platen by detecting a continuous image stretching in a document conveying direction in both of the images having different focal depths, if the images having different focal depths exist.