Image Forming Apparatus Color Calibration via Segmented Sensor Design
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Solution Overview
Problem
Conventional electrophotographic image forming apparatuses face challenges in maintaining accurate color reproducibility due to flare effects caused by reflected light from positions other than the image, especially when there are large differences in luminosity between adjacent color patches, which existing methods struggle to completely eliminate.
Innovation Solution
An image forming apparatus that includes a reading section, a colorimeter, a calibration section, a specification section, and a color adjustment section, which calibrate and adjust the image formation based on measurement data from both the reading section and the colorimeter, allowing for precise color adjustment by moving the colorimeter to positions where it can read images with significant brightness differences, thereby reducing flare effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a CCD line sensor is used for image reading, then image reading can be performed, but flare occurs due to reflected light from positions other than the image, reducing measurement precision
Solution Approach 1:
The patent divides the reading function into two separate devices: a reading section (CCD line sensor) for reading the entire image and a colorimeter for precise color measurement. The colorimeter has a narrower reading width that can be selectively positioned to read only specific color patches, avoiding the flare problem that affects the wider reading section.
Solution Approach 2:
The colorimeter acts as an intermediary device between the reading section and the color adjustment process. It provides accurate color measurement data for specific regions (adjacent color patches with large luminosity differences) that complements the broader image reading data, enabling precise color adjustment without being affected by flare.
2Object-affected harmful factors
If black matte coating or antireflection coat is applied to reduce reflected light, then flare is reduced, but it is difficult to completely eliminate reflected light, so color reproducibility accuracy is still lowered when luminosity difference is large
Solution Approach 1:
The patent extracts the precise color measurement function from the general image reading function. By using a separate colorimeter with a narrow reading width, it can selectively measure only the color patches of interest without being affected by reflected light from adjacent areas, thus taking out the measurement precision requirement from the problematic reading environment.
Solution Approach 2:
The patent applies different reading strategies to different regions: the reading section reads the entire image broadly, while the colorimeter is selectively positioned to read only specific local regions (color patches) where accurate color measurement is critical. This local quality approach ensures high measurement precision where needed without being constrained by the flare problem in the overall reading process.
3Area of stationary object
If the reading section reads over the entire width, then complete image coverage is achieved, but flare from adjacent areas with large luminosity differences affects read values
Solution Approach 1:
The patent segments the reading function into two parts: the reading section covers the entire image width for comprehensive image capture, while the colorimeter provides focused, narrow-width reading of specific color patches. This segmentation allows the system to maintain complete coverage while achieving high measurement precision in critical areas by using the colorimeter's selective reading capability.
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 solution enables high-accuracy color reproduction by effectively addressing flare issues and improving color reproducibility, especially in scenarios with large luminosity differences between adjacent color patches.
Implementation Method 1
phenomenon (flare) which negatively affects read values is generated in some cases due to emitted light being reflected at a position other than the reference image and entering the CCD
Implementation Method 2
a calibration section which calibrates the reading section on the basis of a difference between first reading section measurement data and first colorimeter measurement data
Implementation Method 3
a colorimeter which reads the image over a width smaller than the predetermined width in the width direction of the sheet
Data Source
AI summary
An image forming apparatus, including: an image forming section; a reading section which reads the image formed by the image forming section over a predetermined width in a width direction of the sheet; a colorimeter which reads the image over a width smaller than the predetermined width; a calibration section which calibrates the reading section on the basis of a difference between first reading section measurement data and first colorimeter measurement data; a specification section which specifies adjacent images having a largest difference in brightness of a predetermined threshold value or more from among images for color adjustment formed on the sheet; and a color adjustment section which controls the colorimeter to read at least one of the adjacent images and adjusts a color of the image formed by the image forming section on the basis of second colorimeter measurement data.