Image Reading Apparatus Dirt Detection and Position Adjustment
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Solution Overview
Problem
Image quality deterioration due to dirt or scratches on the original sheet glass plate during running reading in image forming apparatuses like copying machines and scanners, as existing methods either fail to completely eliminate black or white stripes or lead to further image quality degradation.
Innovation Solution
An image reading apparatus equipped with a linear image sensor, an original sheet feeding unit, a discrimination unit to detect abnormal pixel data, and a setting unit that adjusts the reading line to minimize the impact of dirt or scratches by selecting the line with the least continuous abnormal pixel data or total pixel count, thereby optimizing the reading position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If image data is corrected by using adjacent pixel values to compensate for dirt portions, then black or white stripes are eliminated, but image quality deteriorates
Solution Approach 1:
The patent performs preliminary detection of dirt and scratch positions on the original sheet glass plate before the actual reading operation. By detecting abnormal pixels in advance and recording their positions, the system can avoid these areas during reading or apply targeted corrections only where necessary, rather than correcting entire lines. This preliminary action prevents unnecessary image data correction while still eliminating stripes, thus preserving image quality.
2Reliability
If the reading position is changed to avoid dirt portions, then stripe occurrence is reduced, but image quality deteriorates when dirt is present at all set reading positions
Solution Approach 1:
The patent applies different processing strategies to different spatial locations on the original sheet glass plate. By detecting the specific positions of dirt and scratches, the system treats only the affected local areas differently from the rest of the reading surface. Correction or position adjustment is applied locally at dirt/scratch positions rather than globally across the entire reading area, thus minimizing image quality deterioration while still preventing stripe occurrence.
3Measurement precision
If the light scanning unit is stopped during reading to maintain reading position accuracy, then reading precision is improved, but reading speed decreases
Solution Approach 1:
The patent performs preliminary detection of dirt and scratch positions on the original sheet glass plate before the actual reading operation. By detecting abnormal pixels in advance and recording their positions, the system can avoid these areas during reading or apply targeted corrections only where necessary, rather than correcting entire lines. This preliminary action prevents unnecessary image data correction while still eliminating stripes, thus preserving image quality.
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
Minimizes the occurrence of black or white stripes and reduces image quality deterioration by setting the reading position on the line with the least influence from dirt or scratches, even if dirt is present across all set reading positions.
Implementation Method 1
a linear image sensor which photoelectrically converts an optical image obtained by optically scanning an original sheet and reads it in units of line
Data Source
AI summary
When an optical image obtained by an optical scanning unit of optically scanning an original sheet automatically fed by an original sheet feeder is read, it is discriminated in units of pixel whether or not dirt or scratch attached to a running reading glass plate is present. Moreover, the number of the dirt and the width of the dirt are detected, and an image reading position which does not come under the influence of the dirt as much as possible is set based on the detected number of the dirt and the detected width of the dirt even when the dirt is detected at all the reading positions.