Variable Position White Reference and Cleaning Member for CIS Noise Reduction
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Solution Overview
Problem
Image reading apparatuses using CIS technology face issues with foreign substances adhering to the reading surface, leading to image noise streaks due to incomplete cleaning and wear of cleaning members, especially in dual scan reading configurations where high reliability and low noise are required.
Innovation Solution
An image reading apparatus with a variable position white reference member and elastic cleaning member, controlled by a controller to alternately move between cleaning and reading positions, ensuring thorough cleaning and accurate shading correction by calculating reference values from multiple detection readings before and after cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the document is brought close to the CIS for reading, then reading accuracy is improved, but adhesive foreign substances are easily transferred from the document to the CIS
Solution Approach 1:
The patent applies preliminary action by performing shading correction using a white reference sheet before actual document reading. This preliminary reading establishes baseline data that helps distinguish between normal document variations and foreign substance artifacts, allowing the system to compensate for transferred substances during the correction process
Solution Approach 2:
The patent implements feedback mechanisms by repeatedly reading the white reference sheet at multiple positions and using the collected data to calculate and apply shading correction values. This feedback loop allows the system to detect and compensate for foreign substance transfer by comparing readings against the established baseline
2Reliability
If cleaning operations are performed frequently to remove foreign substances, then image quality is improved, but cleaning members wear out faster
Solution Approach 1:
The patent replaces mechanical cleaning systems with a white reference sheet-based optical correction system. Instead of physically cleaning the CIS sensor, the system uses optical readings and computational algorithms to remove the visual impact of foreign substances, thereby eliminating mechanical wear on cleaning members
Solution Approach 2:
The patent changes the approach from physical removal to optical parameter adjustment. By modifying the shading correction parameters based on white reference sheet readings, the system compensates for foreign substance effects without requiring physical cleaning, thus preserving cleaning member durability
3Measurement precision
If shading correction is made for each job, then reading density accuracy is improved, but image noise streaks occur when foreign substances are present on the CIS
Solution Approach 1:
The patent performs preliminary readings of the white reference sheet at multiple positions before actual document reading. This preliminary action collects baseline data that is used to calculate shading correction values, enabling the system to distinguish between normal shading variations and foreign substance artifacts
Solution Approach 2:
The patent performs more readings than strictly necessary by reading the white reference sheet at multiple positions and performing multiple shading correction calculations. This excessive action ensures that even if some readings are affected by foreign substances, the majority of valid readings can be used to establish accurate correction values
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
Enhances image quality by effectively removing foreign substances and reducing noise streaks, while extending the durability of cleaning members and maintaining low noise levels, even with frequent cleaning operations.
Implementation Method 1
an elastic member... for coming into contact with a surface of the transparent member facing toward the conveying path and cleaning the surface
Implementation Method 2
a reading mechanism for reading, through the transparent member, the document conveyed along the conveying path
Data Source
AI summary
In an image reading apparatus, a white reference member for obtaining a reference value used in shading correction in the reading mechanism and an elastic member for cleaning a surface of the transparent member are provided such that respective positions of the white reference member and the elastic member with respect to the transparent member are variable. A controller controls the positions of these members with respect to the transparent member to alternately achieve movement of the white reference member to a position where the white reference member faces the transparent member and movement of the elastic member to a position where the elastic member faces the transparent member. The controller calculates the above reference value using a plurality of detection values read by the reading mechanism through the above positional control.