Positional Error Detection Marks for Color Registration
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Solution Overview
Problem
In tandem type image forming apparatuses, positional errors between color images lead to unstable color registration due to misalignment of light emitting and receiving elements, causing errors in detecting toner images, especially when mechanical tolerances or assembly errors introduce discrepancies in the reflection light components.
Innovation Solution
A positional error detection method and apparatus that uses a transport belt with specifically designed positional error detection marks, including first and second marks inclined in opposite directions and third marks perpendicular to the transport direction, to improve accuracy by forming and detecting these marks using sensors, and computing the positional error based on their positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional detection method using light emitting and receiving elements is used, then positional error detection is possible, but detection accuracy deteriorates due to misalignment from mechanical tolerance and assembling error
Solution Approach 1:
The patent creates optical copies (images) of the positional error detection marks on the photoconductive drum surface, then detects these copied images using the reading means. This allows detection based on the copied positional information rather than direct mechanical measurement, reducing the impact of mechanical tolerance and assembly errors on detection accuracy
Solution Approach 2:
The patent introduces the photoconductive drum as an intermediary medium. The light emitting means projects light to create images of the detection marks on the drum surface, and the reading means reads these images. This intermediary system decouples the detection process from direct mechanical alignment requirements between light emitting and receiving elements, improving both accuracy and reliability
2Device complexity
If light emitting element and light receiving element alignment is not perfect, then detection process is simpler, but peak positions of regular and diffused reflection light components do not match, introducing error
Solution Approach 1:
The system creates optical copies of the detection marks on the photoconductive drum and detects these copies. This copying approach allows the detection to be based on the reproduced positional information rather than direct optical path alignment, reducing sensitivity to misalignment between light emitting and receiving elements
Solution Approach 2:
The patent transitions from direct optical detection in one dimension (direct line of sight between light emitting and receiving elements) to a two-dimensional detection approach using the photoconductive drum surface as an intermediate plane. This dimensional change allows detection without requiring precise alignment in the original optical path
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 enhances the accuracy of positional error detection between reference and other colors, effectively canceling out detection errors caused by unstable rotations and mechanical inaccuracies, resulting in improved color registration stability.
Implementation Method 1
a photoconductive drum 9BK, 9M, 9C and 9Y, a charging unit 10BK, 10M, 10C and 10Y, an exposure unit 11
Implementation Method 2
The reflected light detected by the detecting means includes a regular (or mirror) reflection light component and a diffused reflection light component
Data Source
AI summary
A positional error detection method forms, on a belt which is transported in a transport direction, positional error detection marks for detecting a positional error between image positions of first and second colors, detects the positional error detection marks on the belt, and computes the positional error based on the detected positional error detection marks. The positional error detection marks include first and second marks which are inclined in mutually opposite directions with respect to the transport direction, and third marks which are perpendicular to the transport direction.