Overlapping Toner Pattern for Image Positional Shift Correction
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Solution Overview
Problem
Existing image forming apparatuses face challenges in accurately correcting positional shifts of images due to color shifts, which are exacerbated by the high toner consumption and instability in detecting toner patches.
Innovation Solution
The apparatus includes a sensor with a light emitting element and a light receiving element to detect a correction pattern on an intermediate transfer member, and a controller that adjusts the image forming units to form an overlapping pattern with specific toner image configurations, optimizing the dynamic range for stable detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If overlapping patches are formed by overlapping a black patch on a yellow patch, overlapping a black patch on a cyan patch, and overlapping a black patch on a magenta patch, then the color shift can be corrected, but the amount of toner consumption increases
Solution Approach 1:
The patent applies local quality by forming an overlapping pattern where a first monochromatic toner image (e.g., black) is overlapped on a second monochromatic toner image (e.g., yellow, cyan, or magenta) only in specific regions where color shift correction is needed. This localized overlapping approach corrects color shift at the patch level rather than requiring full overlapping patches, thereby reducing overall toner consumption while maintaining correction accuracy.
Solution Approach 2:
The patent uses partial action by forming the overlapping pattern with a smaller area second monochromatic toner image overlapped on the first monochromatic toner image. The second toner image covers only the necessary portion for detection and correction, rather than creating complete overlapping patches. This partial overlapping approach achieves sufficient detection signal for color shift correction while minimizing toner usage.
2Quantity of substance
If the amount of toner is decreased in the correction pattern, then toner consumption is reduced, but it becomes difficult to stably detect the toner patch
Solution Approach 1:
The patent applies parameter changes by optimizing the dynamic range D of the overlapping pattern to be between 0.5 and 1.0. This dynamic range is calculated from received light amounts V1 and V2 from the first and second monochromatic toner images, respectively. By controlling this parameter, the patent ensures sufficient detection stability even with reduced toner amounts, as the optimized dynamic range provides an ideal signal contrast for the detection sensor.
Solution Approach 2:
The patent replaces the mechanical approach of using large overlapping patches with sufficient toner coverage with an optical detection approach. By using a detection sensor to measure the dynamic range D based on light reflection from the overlapping pattern, the system can reliably detect color shifts with minimal toner consumption. The optical detection method substitutes for the need for large toner quantities, achieving stable detection through precise measurement rather than material abundance.
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 efficient correction of image positional shifts while reducing toner consumption and improving detection stability, ensuring accurate reproduction of input images.
Implementation Method 1
a light receiving element configured to receive light reflected by either the intermediate transfer member or the correction pattern among the light outputted from the light emitting element
Implementation Method 2
an exposure unit configured to form an electrostatic latent image by exposing a surface of the image carrier
Implementation Method 3
a developing unit configured to form a toner image by developing, by toner, the electrostatic latent image formed on the surface of the image carrier by the exposure unit
Data Source
AI summary
An image forming apparatus receives light from an intermediate transfer member or a correction pattern. The pattern includes an overlapping pattern on which a first monochromatic toner image is formed as a lower layer and a second monochromatic toner image having a smaller area than the first monochromatic toner image is formed as an upper layer. The image forming apparatus controls a plurality of image forming units to form the overlapping pattern such that a dynamic range becomes less than 1.0 and greater than 0.5.