Polygonal Mirror Color Misregistration Timing Control
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Solution Overview
Problem
Conventional color image forming apparatuses with a single polygonal mirror for multiple photosensitive bodies face challenges in adjusting color misregistration due to the inability to adjust the rotational phase of the mirror on a color-by-color basis, leading to maximum color misregistration of one pixel in the sub-scan direction.
Innovation Solution
The solution involves sensing the color misregistration of each toner image formed by a single rotating polygonal mirror with multiple mirror surfaces and controlling the light-emission timings to ensure that the misregistration is less than (n−1)/n pixels, where n is the number of photosensitive bodies, allowing for precise adjustment of the mirror surface for each color.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single polygonal mirror is used for multiple photosensitive bodies to reduce cost and size, then device complexity is reduced, but color misregistration adjustment capability deteriorates
Solution Approach 1:
The single polygonal mirror is segmented into multiple mirror surfaces, with each surface dedicated to a specific photosensitive body. This segmentation allows independent adjustment of each mirror surface's rotational phase, enabling color misregistration correction for each color channel while maintaining a compact single-mirror structure.
Solution Approach 2:
Each mirror surface of the polygonal mirror is assigned a specific function for a particular photosensitive body, creating local specialization. This allows different mirror surfaces to have different rotational phases optimized for their respective color channels, resolving the color misregistration issue without requiring separate mirrors for each color.
2Manufacturing precision
If light-emission timings are controlled to match specific mirror surfaces, then color misregistration is reduced to less than (n-1)/n pixels, but control complexity increases
Solution Approach 1:
The system performs preliminary adjustment of light-emission timings during the setup phase to match each laser source with its corresponding mirror surface rotational phase. This preliminary calibration establishes the correct timing relationships, after which the system operates with stable, pre-determined timing control, minimizing ongoing complexity.
Solution Approach 2:
The system uses beam detection signals from each scanning optical path to monitor the actual rotational phase of the polygonal mirror. This feedback information is used to adjust and maintain the correct light-emission timings, ensuring color misregistration remains below the (n-1)/n pixel threshold while automating the control process.
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 results in a low-cost, compact, high-quality color image forming apparatus with reduced color misregistration in the sub-scan direction, improving image quality by ensuring that color misregistration is less than (n−1)/n pixels, thereby enhancing the overall performance of the color printer.
Implementation Method 1
a single rotating polygonal mirror with multiple mirror surfaces... light beams from a plurality of light sources are concurrently deflected and scanned by the single polygonal mirror
Implementation Method 2
The laser beam forms an image on the photosensitive drum via an imaging lens to thereby form an electrostatic latent image
Data Source
AI summary
An electrophotographic image forming apparatus senses amounts of color misregistration of toner images, which are formed using n-number (where n is a natural number and n=2 holds) of photosensitive bodies, when light beams from a plurality of light sources are made to deflect and scan across the n-number of photosensitive bodies by a single rotating polygonal mirror. The timing of light emission from the light sources is controlled in such a manner that light beams from the light sources will be deflected and scanned by mirror surfaces of the polygonal mirror, from among the plurality of mirror surfaces that form the polygonal mirror, such that the amount of color misregistration of every toner image will be less than (n−1)/n pixels.