Color Registration Correction Using Skew Calculation
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Solution Overview
Problem
Existing image forming apparatuses face challenges in accurately aligning colors in the main scanning direction, leading to errors in image registration, as conventional registration sensors are limited in their ability to correct pixel position uniformity across colors, increasing manufacturing costs and reducing registration accuracy.
Innovation Solution
An image forming apparatus and method that print multiple lines at predetermined intervals in the main scanning direction, using different photosensitive drums, and a processor to perform color registration correction by calculating skew values from specific sub-lines, allowing for error correction without the need for multiple registration sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple registration sensors are arranged in the main scanning direction to improve color registration accuracy, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent uses a single registration sensor to scan multiple lines printed at different positions in the main scanning direction. By creating multiple measurement copies (lines) with the same sensor, the system achieves comprehensive color registration measurement without needing multiple sensors physically arranged across the main scanning direction.
Solution Approach 2:
The patent transitions from measuring color registration at a single point to measuring along the main scanning direction by printing multiple lines. This dimensional approach allows one sensor to capture registration errors across the entire main scanning range by scanning different line positions sequentially.
2Device complexity
If a single registration sensor is used to reduce device complexity, then manufacturing cost is reduced, but measurement precision deteriorates due to limited coverage in the main scanning direction
Solution Approach 1:
The patent divides the color registration measurement task into multiple segments by printing several lines at different main scanning positions. Each line provides measurement data for a specific segment of the main scanning direction, and the registration sensor scans these segmented lines to achieve comprehensive coverage.
Solution Approach 2:
The registration sensor performs periodic scanning actions across multiple lines printed at predetermined intervals. By sequentially scanning each line and accumulating measurement data, the single sensor achieves comprehensive color registration measurement across the entire main scanning direction.
3Manufacturing precision
If exposure start time points of photosensitive drums are accurately matched to improve color registration, then manufacturing precision is improved, but pixel position uniformity in the main scanning direction deteriorates
Solution Approach 1:
The patent uses the registration sensor to detect pixel position deviations in the main scanning direction and feeds back correction information to adjust the exposure timing of photosensitive drums. This feedback mechanism compensates for non-uniform pixel positions that cannot be corrected by timing synchronization alone.
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 improves color registration accuracy in the main scanning direction, reducing manufacturing costs and enhancing image quality by correcting errors without relying on extensive registration sensor arrays.
Implementation Method 1
a scanner configured to scan the printing paper on which the plurality of lines are printed
Data Source
AI summary
An image forming apparatus includes a plurality of photosensitive drums respectively corresponding to a plurality of colors to print, on a recording medium, color chart of a plurality of vertical lines in a sub-scanning direction to a main scanning direction of the recording medium and to be arranged at intervals along the main scanning direction. A vertical line of the plurality of vertical lines includes at least two colored sub-lines to be formed by corresponding at least two photosensitive drums. A processor is to perform a correction in non-linear color registrations in the main scanning direction using an image of the color chart.