Rotating Reference Roller Shading Correction Contamination
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Solution Overview
Problem
Image reading apparatuses face irregularities in image data generation due to variations in illumination and vignetting, which can be exacerbated by contaminants on the reference surface, leading to inaccurate shading correction.
Innovation Solution
An image reading apparatus with a shading correction unit that determines the presence of contaminants on the reference surface and generates reference data only from clean areas, using a rotating reference roller to prevent contamination and ensure accurate shading correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stationary reference plate is used for shading correction, then the structure is simple and easy to manufacture, but contaminants can accumulate on the reference surface leading to inaccurate reference data
Solution Approach 1:
The patent applies the dynamics principle by replacing the stationary reference plate with a rotating reference roller. The reference roller rotates to present different surfaces to the image sensor, including a reference surface and a standby surface. This dynamic configuration prevents contaminant accumulation on the reference surface by periodically exposing clean areas, thereby maintaining the reliability of shading correction without significantly increasing structural complexity.
2Reliability
If a rotating reference roller is used to prevent contamination, then the reliability of reference data is improved, but the device complexity increases
Solution Approach 1:
The patent applies the universality principle by designing the reference roller to serve multiple functions: it acts as both the reference surface for shading correction and a protective element that rotates to expose clean areas. The reference roller integrates the reference surface, standby surface, and contamination prevention mechanism into a single component, thereby improving reliability while minimizing the increase in device complexity compared to using separate stationary reference plates.
3Measurement precision
If the reference surface is always exposed to the image sensor, then the measurement process is simple, but contaminants on the reference surface degrade measurement precision
Solution Approach 1:
The patent applies the periodic action principle by rotating the reference roller to periodically expose different surfaces (reference surface and standby surface) to the image sensor. This periodic rotation ensures that even if contaminants accumulate on one surface, clean areas are periodically presented for accurate measurement, maintaining measurement precision while requiring only simple control mechanisms that do not significantly impact processing speed.
Data Source
AI summary
An image reading apparatus according to an embodiment includes an image reading unit configured to generate reference data by reading a reference surface and to generate image data by reading a sheet. A reference unit has a reference surface. A shading correction unit determines whether a portion of the reference surface includes a contaminant based on image data generated by the image reading unit reading the portion of the reference unit. When the portion of the reference surface is determined to not include a contaminant, the shading correction unit generates reference data based on the image data generated by the image reading unit reading the portion of the reference surface determined to not include a contaminant.