Color Registration Correction in Electrophotographic Printers
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Solution Overview
Problem
Conventional color registration correction systems in electro-photographic printers face errors due to changes in roller diameter and surface defects on the image carrying medium, leading to inaccurate exposure start points and registration errors.
Innovation Solution
A system with a color registration controller that uses a mark sensing unit to detect developed marks on the image carrying medium, storing time points and comparing them to the number of marks, and adjusting exposure start points to ensure accurate color registration, including a detection memory unit and a correction value calculation unit to handle disturbances and errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors detect marks on the image carrying medium for color registration correction, then correction values can be calculated to adjust exposure start points, but surface defects or disturbances may be falsely detected as marks leading to erroneous correction values
Solution Approach 1:
The detection memory unit is divided into multiple detection memory devices, each corresponding to a specific mark position. This segmentation allows the system to track and verify individual mark detections, making it easier to identify and eliminate false detections caused by surface defects.
Solution Approach 2:
The system uses feedback by comparing the number of detected marks with the expected number of marks. When the counts match, the correction values are considered reliable; when they differ, the system can identify potential false detections and adjust accordingly.
2Adaptability or versatility
If the roller diameter changes due to thermal expansion during printing, then the transfer speed of the image carrying medium changes even at constant rotation rate, but this makes it difficult to maintain accurate color registration
Solution Approach 1:
The system dynamically adjusts exposure start points based on real-time detection of mark positions. Instead of using fixed initial values, the exposure start points are continuously corrected according to the actual positions detected by the sensors, allowing the system to adapt to roller diameter changes and maintain registration accuracy.
Solution Approach 2:
The system implements a feedback loop where mark positions are detected, correction values are calculated based on position deviations, and exposure start points are adjusted accordingly. This closed-loop control enables the system to compensate for thermal expansion and maintain accurate color registration despite changing operating conditions.
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 allows for accurate calculation and application of correction values, ensuring proper color registration and clear image printing by dynamically adjusting exposure start points based on detected mark positions and removing errors caused by surface disturbances.
Implementation Method 1
an exposure unit projects light beams on the photosensitive drum to form latent images
Implementation Method 2
a developing unit develops the latent images formed by the exposure unit for each color with a developing solution
Data Source
AI summary
Disclosed are an apparatus for and a method of correction color registration in an electro-photographic printer. An apparatus for correcting color registration in an electro-photographic printer, in which exposure start points of each color unit for a photosensitive drum are adjusted to superpose images developed in a plurality of colors on matching positions of a transfer belt, includes an exposure unit to project light beams on the photosensitive drum to form latent images of one or more marks for each color unit. A developing unit is also disclosed to generate developed images by developing the latent images of the marks and a mark sensing unit is provided to detect the developed images transferred on a surface of the transfer belt for a predetermined time period. A color registration controller stores information on time points at which the developed images are detected and compares the number of the time points with the number of the marks. Thus, the color registration controller controls the exposure start points in response to the compared result.