Polygon Mirror Scanning Line Length Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In image forming apparatuses using electrophotography, length variations of scanning lines formed by polygon mirror reflection surfaces cause color misregistration and moiré, limiting the use of screens due to uncorrected tolerances and interference patterns.
Innovation Solution
A system that generates pulse signals to modulate laser beams based on image data, inserting or deleting pulse signals of specific widths to adjust scanning line lengths closer to a reference value, thereby correcting deviations and reducing moiré formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a rotating polygon mirror is used to scan the photosensitive member with a laser beam, then scanning speed and image formation efficiency are improved, but length variations of scanning lines occur due to tolerances of reflection surfaces, causing moiré patterns
Solution Approach 1:
The patent applies parameter changes by adjusting the pulse signal width dynamically based on the reflection surface being used. Different pulse widths are assigned to different reflection surfaces to compensate for their respective length deviations, thereby normalizing the scanning line lengths despite manufacturing tolerances in the polygon mirror.
Solution Approach 2:
The patent implements feedback by measuring or pre-determining the actual scanning line lengths for each reflection surface and using this information to generate appropriate pulse signals. The generating device receives information on deviation amounts and adjusts the pulse width accordingly, creating a closed-loop correction system.
2Device complexity
If tolerances of reflection surfaces are not corrected, then device complexity is reduced, but moiré patterns are generated due to interference between rotating polygon mirror cycles and screen patterns
Solution Approach 1:
The patent applies preliminary action by pre-determining or measuring the deviation amounts of each reflection surface before actual image formation. This information is stored and used to generate corrected pulse signals in advance, avoiding the need for complex real-time adjustments during scanning.
Solution Approach 2:
The patent changes the pulse signal parameter (width) based on the specific reflection surface being used. By assigning different pulse widths to different reflection surfaces according to their deviation characteristics, the system compensates for manufacturing tolerances and eliminates moiré patterns without requiring complex mechanical adjustments.
3Manufacturing precision
If pulse signal width is adjusted for each reflection surface, then scanning line length variations are suppressed, but image data processing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the appropriate pulse widths for each reflection surface based on their deviation characteristics. During actual operation, the system simply retrieves the pre-determined pulse width for the current reflection surface, avoiding complex real-time calculations and reducing processing burden.
Solution Approach 2:
The patent applies local quality by tailoring the pulse signal parameters specifically for each reflection surface based on its individual deviation characteristics. Instead of using a uniform pulse width for all surfaces, the system assigns optimized local parameters to each surface, improving precision while keeping the overall control strategy manageable through systematic organization.
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 effectively suppresses scanning line length variations, reduces moiré, and relaxes constraints on screen design, enhancing the image forming apparatus's performance and flexibility.
Implementation Method 1
a polygon mirror formed with a plurality of reflection surfaces, and configured to scan the photosensitive member with the laser beam by reflecting the laser beam by the reflection surfaces of the rotating polygon mirror
Implementation Method 2
scanning device including a light source configured to emit a laser beam
Data Source
AI summary
An image forming apparatus includes: a polygon mirror formed with a plurality of reflection surfaces, and a generating device configured to generate a pulse signal required to modulate a laser beam based on image data. The generating device is further configured to generate a pulse signal by inserting or deleting a pulse signal having a width smaller than a width of a pulse signal corresponding to one pixel of the image data into or from a pulse signal corresponding to the image data based on information associated with deviation amounts between lengths of scanning lines formed by the plurality of reflection surfaces and a reference value, so as to adjust the lengths of the scanning lines formed by the plurality of reflection surfaces to be closer to the reference value.