Mark Position Detection Slope Correction
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Solution Overview
Problem
Tandem-type image forming apparatuses face inaccuracies in color registration due to errors in determining the displacement of images, leading to color shifts, as the estimated displacement amounts may not be accurately determined, resulting in inaccuracy in final displacement correction.
Innovation Solution
The image forming apparatus includes a forming portion, a control portion, a light receiving portion, a determining portion, a correcting portion, and an adjusting portion to form and correct images based on a registration pattern and a corrective pattern, using optical sensors to detect light variations and adjust image positions with higher correction values for smaller slope changes, thereby improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the position of the mark is determined based on comparison of light level with threshold, then the mark position can be detected automatically, but the detected position may have error when the slope of level change is small
Solution Approach 1:
The patent changes the parameter of threshold selection from a fixed value to a dynamic value that adapts to the local characteristics of the light level signal. By calculating the average light level in a neighborhood around the detection point and using this as an adaptive threshold, the system accounts for variations in slope and ensures accurate mark position detection regardless of the signal's gradient characteristics.
2Productivity
If a fixed threshold is used for mark detection, then the detection process is simple and fast, but detection accuracy deteriorates when mark characteristics vary
Solution Approach 1:
The patent performs preliminary calculation of the average light level in the neighborhood of the detection point before determining the mark position. This preliminary action creates an adaptive threshold that is specific to the local characteristics of each mark, enabling accurate detection without requiring complex real-time adjustments during the detection process itself.
3Measurement precision
If correction value is increased for small slope changes, then detection accuracy is improved, but the complexity of the correction process increases
Solution Approach 1:
The patent implements a feedback mechanism where the detected mark position and light level characteristics are used to calculate an appropriate correction value. The system feeds back the local average light level information to adjust the detection threshold, creating a self-correcting process that improves accuracy without requiring external intervention or complex manual calibration.
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 enhances the accuracy of image positioning corrections, reducing color shifts and improving the overall precision of color registration in image forming processes.
Implementation Method 1
a light receiving portion configured to receive a light from a detection area, a level of the light varying with time while an image formed on the object moves across the detection area with the relative movement of the object
Data Source
AI summary
A light receiving portion is configured to receive light that varies with time while a mark formed on an object moves across a detection area. The position of the mark on the object is determined based on comparison of a time-varying level of the light with at least one threshold during movement of the mark on the object across the detection area. The determined position of the mark is corrected by a correction value into a corrected mark position. The correction value is set to a higher value, if the time-varying light level exceeds the threshold or falls below the threshold with a smaller slope while the mark moves across the detection area. An image forming position is adjusted based on the corrected mark position.