Polygon Mirror Phase Control for Color Registration
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Solution Overview
Problem
Electrophotographic image forming apparatuses face challenges in maintaining accurate color registration and density correction due to environmental changes and skewed sheet feeding, leading to inefficiencies in image formation and increased standby times.
Innovation Solution
The apparatus includes multiple image forming units with photoreceptors and laser scanners, an intermediate transfer member, optical sensors, and a control unit that adjusts the phase relation and emission timing of rotating polygon mirrors to correct skew and registration issues without delaying image formation, allowing for precise color registration and density detection without affecting productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the phase relation of rotating polygon mirrors is controlled when forming a density correction test image, then color registration precision is improved, but image formation time is increased due to delayed start
Solution Approach 1:
The patent segments the control process into two distinct modes: a first control mode for color registration correction that controls the phase relation of polygon mirrors, and a second control mode for density correction that does not control the phase relation. This segmentation allows the system to apply phase control only when necessary for color registration, avoiding unnecessary time delays during density correction operations.
Solution Approach 2:
The patent implements dynamic switching between different control modes based on the operational requirements. The control unit dynamically selects between the first control mode (with phase relation control) and the second control mode (without phase relation control) depending on whether color registration correction or density correction is being performed, optimizing both precision and efficiency for each specific task.
2Measurement precision
If color registration correction is performed by controlling phase relation of polygon mirrors, then color registration accuracy is improved, but productivity is reduced due to increased standby time
Solution Approach 1:
The patent divides the operational modes into segmented control strategies: the first control mode enables precise color registration correction through phase relation control of polygon mirrors, while the second control mode operates without phase relation control to maintain higher productivity during density correction tasks, thus optimizing the balance between accuracy and productivity.
Solution Approach 2:
The patent changes the control parameters dynamically based on the operational mode. During color registration correction, the phase relation parameter of polygon mirrors is controlled to achieve high accuracy. During density correction, this parameter control is suspended to reduce standby time and maintain productivity, effectively using parameter changes to resolve the contradiction.
3Manufacturing precision
If the image is inclined to correct skewed sheet feeding, then position registration is improved, but writing start timing in sub-scanning direction changes causing color misregistration
Solution Approach 1:
The patent applies preliminary anti-action by controlling the phase relation of polygon mirrors in advance to compensate for the color misregistration that would result from image inclination. When sheets are fed skewed and the image is inclined for position registration, the phase control pre-adjusts the polygon mirror timing to counteract the resulting color alignment issues, achieving both position and color registration simultaneously.
Solution Approach 2:
The patent employs feedback mechanisms where the detection results from optical sensors detecting test images are used to determine appropriate phase relation control settings. The control unit adjusts the phase relation of polygon mirrors based on feedback from position registration detection, enabling dynamic compensation for color misregistration caused by image inclination while maintaining accurate position registration.
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 enables precise color registration correction and density detection with reduced standby times, enhancing the productivity and accuracy of image formation by controlling the phase relation and emission timing of the rotating polygon mirrors based on skew and detection results.
Implementation Method 1
a first rotating polygon mirror which reflects the first laser light such that the first laser light scans the first photoreceptor
Implementation Method 2
The electrophotographic system image forming apparatus forms color images by forming electrostatic images by irradiating laser light to each of the photoreceptors
Implementation Method 3
By detecting the test image formed by a sensor, the image forming apparatus obtains density information representing the density of the image or position registration information
Data Source
AI summary
The image forming apparatus controls each laser scanner by setting the writing start timing in the sub-scanning direction to form the color registration correction image for correcting color registration at position according to the detection result of the image detection sensor. When forming the image on the sheet, the image forming apparatus sets the writing start timing in the sub-scanning direction according to the detection result of the image detection sensor and the amount of skew of the sheet to control each laser scanner. When forming the density detection toner image for correcting the density, the image forming apparatus sets the writing start timing in the sub-scanning direction to form the image at a position shifted by a pixel unit from the image forming position on the sheet.