Image-Forming Device Registration Mark Calibration
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Solution Overview
Problem
In electrophotographic image-forming devices, foreign matter or scratches on photosensitive members can cause unintended blemishes that interfere with registration error detection, leading to a dramatic drop in accuracy for correcting registration errors, especially when blemishes form at every rotational period of the photosensitive member.
Innovation Solution
The device employs multiple rotatable photosensitive drums with registration marks of different colors, spaced at specific intervals, to ensure accurate detection and calibration of image-forming positions, even when blemishes occur, by forming marks that satisfy equations such as D=N×M×L+(M−1)×L, where D is the circumference, L is the distance between marks, and N is an integer, thereby distributing the impact of blemishes across all colors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If marks are formed at positions of opposite phase relative to the rotational period of the photosensitive member to prevent dynamic positional offset, then registration error detection accuracy is improved, but blemishes formed every rotational period can be misinterpreted as marks, causing a dramatic drop in detection accuracy for marks of that color
Solution Approach 1:
The patent divides the detection system into multiple independent detection positions around the photosensitive member's circumference. By forming marks at multiple positions (including opposite phase positions) and detecting them with corresponding sensors, the system segments the detection function across multiple locations. This allows the system to maintain reliable detection even when blemishes affect one particular position, as other positions remain unaffected.
Solution Approach 2:
The patent applies local quality by assigning different functional roles to marks at different positions. Marks at opposite phase positions serve specific calibration functions for correcting dynamic positional offsets, while marks at other positions provide redundancy against blemish interference. The detection system evaluates marks locally at each position and can selectively weight or discard results based on local conditions, maintaining overall detection reliability.
2Manufacturing precision
If multiple marks are formed to detect registration error, then the ability to correct registration error is improved, but blemishes can interfere with mark detection, reducing the accuracy for detecting positions of marks
Solution Approach 1:
The patent implements feedback by using the detection results from multiple marks to continuously refine and correct registration error. The system detects positions of multiple marks, calculates registration errors based on these detections, and uses this feedback to adjust the imaging process. This closed-loop feedback mechanism ensures that even if some marks are affected by blemishes, the overall registration accuracy is maintained through corrective adjustments based on reliable detections.
Solution Approach 2:
The patent forms more marks than the minimum required for basic registration detection. By creating multiple marks at different positions around the photosensitive member, the system provides excessive redundancy. This allows the detection system to select and use only the reliable marks for correction, ignoring those affected by blemishes, thereby maintaining high detection accuracy through partial use of the available marks.
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 configuration maintains high accuracy in correcting registration errors by evenly distributing the adverse effects of blemishes across all colors, preventing a dramatic decrease in precision and ensuring reliable image formation.
Implementation Method 1
detects the positions of the marks with a photosensor
Data Source
AI summary
An image-forming device includes 1st to Mth photosensitive drums (which are arrayed in numeric order in a first direction), a forming unit, an image-carrying member, a detecting unit, and a calibrating unit. Each of the photosensitive drums has a circumferential length D and extends in a first direction. The forming unit forms a registration mark on each of the photosensitive drums. The registration marks are transferred onto the image-carrying member in the numeric order and are arrayed in the first direction. Neighboring registration marks are spaced by a distance L in the first direction. The detecting unit detects positions of the registration marks. The calibrating unit calibrates positions of the photosensitive drums based on the positions detected by the detecting unit. D=NxMxL+(M−1)xL. N being an integer not less than 0.