Image Reading Apparatus Roller Shading Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional image reading techniques in devices like copying machines and scanners face efficiency decreases and image degradation due to the need for frequent movement to a white reference plate for shading correction, which affects the entire main scanning region's luminous intensity distribution.
Innovation Solution
An image reading apparatus and method that utilize a density reference member, a roller member, and a comparison device to read and correct image signals, allowing for continuous operation without significant decreases in efficiency by reading the roller member between originals to adjust for luminous intensity variations, thereby maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If movement to the white reference plate is performed at predetermined timing for shading correction, then light quantity correction is achieved, but reading efficiency greatly decreases
Solution Approach 1:
The roller member serves dual purposes: it both feeds the original document and acts as a reference member for luminous intensity distribution correction. By utilizing the roller member that is already present in the reading path for correction purposes, the system eliminates the need for separate reference plate movements, thereby maintaining reading efficiency while achieving correction
Solution Approach 2:
The roller member performs multiple functions: it acts as both a feeding mechanism for the original document and as a reference member for luminous intensity distribution correction. This multi-functionality resolves the contradiction by using an existing component for dual purposes, avoiding the efficiency loss associated with dedicated reference plate movements
2Reliability
If an end white plate is used for monitoring light quantity, then correction can be performed on basis of variation amount, but variations in luminous intensity distribution in the entire main scanning region cannot be corrected
Solution Approach 1:
Instead of using a single end white plate for correction, the invention divides the correction into multiple local measurement points along the main scanning direction. The roller member is read at multiple positions, allowing luminous intensity distribution variations across the entire scanning region to be detected and corrected locally at each position
Solution Approach 2:
The correction process is segmented into multiple reading operations at different positions along the roller member. By reading the roller member at multiple locations rather than relying on a single end plate measurement, the system can capture and correct luminous intensity variations across the entire main scanning region
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 prevents image degradation and maintains reading efficiency by continuously correcting luminous intensity distribution variations without the need for frequent reference plate movements, ensuring consistent image quality throughout the scanning process.
Implementation Method 1
a reading device which photoelectrically converts light reflected by the object and reads information on the object
Data Source
AI summary
An object of this invention is to suppress a decrease in reading efficiency while preventing image degradation. To achieve this object, an image reading apparatus includes a light source which illuminates an object, a sensor which photoelectrically converts light reflected by the object and reads information on the object, a first density reference member which serves as a reference for correcting an image signal obtained by reading an original by the sensor, a second density reference member which is different from the first density reference member, a comparison unit which compares the second signal obtained by reading the second density reference member by the sensor and the third signal obtained by reading again the second density reference member by the sensor, and a correction unit which corrects the image signal on the basis of the first signal obtained by reading the first density reference member by the sensor, and the comparison result of the comparison device.