Image Forming Apparatus Calibration Using Reflectance Correction
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Solution Overview
Problem
Existing image forming apparatuses face challenges in maintaining image quality due to variations in usage environments and printing media types, as they require specific calibration media and do not accurately account for differences in reflectance, leading to potential toner imbalances and reduced calibration accuracy.
Innovation Solution
The solution involves adjusting the luminance value output from an image reading apparatus based on the type of printing medium used for calibration, using correction coefficients and lookup tables to account for reflectance differences, allowing calibration with a second printing medium while maintaining tone characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If calibration is performed using a specific type of printing medium (first printing medium), then the tone characteristic for that medium can be maintained, but no calibration can be performed when that medium runs out
Solution Approach 1:
The patent enables the image reading apparatus to read images from multiple types of printing media (transparency sheets, plain paper, coated paper) by providing separate reading paths for transmitted light and reflected light. This allows calibration to be performed using any of these media types, making the calibration function universal across different media kinds while maintaining reliability.
2Adaptability or versatility
If an arbitrary type of printing medium (second printing medium) is added for calibration, then a wide variety of printing media become usable, but the amount of applied toner may become insufficient or exceed permissible range
Solution Approach 1:
The patent changes the reading parameter (transmitted light or reflected light) based on the type of printing medium being used for calibration. By selecting the appropriate light path according to the medium type, the system achieves accurate reading values that lead to correct toner application amounts, preventing both insufficient and excessive toner application across various media types.
3Ease of operation
If calibration is performed using a printing medium different from the designated type, then operator convenience is improved, but the reflectance difference causes high-accuracy calibration to become unachievable
Solution Approach 1:
The patent applies different reading methods (transmitted light for transparency sheets, reflected light for plain paper and coated paper) according to the local characteristics of each printing medium type. This localized approach ensures that each medium type is read in the most appropriate manner, maintaining high calibration accuracy while allowing operators to use any medium type for convenience.
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 improves calibration accuracy and maintains image quality by optimizing toner application and accounting for varying reflectance, enabling effective calibration with different printing media types.
Implementation Method 1
The reflectance of the background where no toner image is formed on the surface of a printing medium changes depending on the type of printing medium
Data Source
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AI summary
An image forming apparatus 100 forms a pattern image on a first printing medium X and creates a first image processing condition (LUTa) for adjusting a tone characteristic based on a first luminance value (I(X)). When performing the calibration using a second printing medium Z different from the first printing medium X, the apparatus 100 corrects, based on a luminance value of a background region of the second printing medium Z, a second luminance value (I(Z)) output in accordance with light reflected by the second printing medium Z, and creates the first image processing condition (LUTa) based on the corrected second luminance value (I'(Z)).