Laser Scanning Timing Control for Accurate Color Overlay
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Solution Overview
Problem
The accuracy of image stacking in color laser printers is compromised by varying printing environments such as temperature and humidity, necessitating adjustments in laser scanning unit control to maintain high image quality.
Innovation Solution
A laser scanning unit with dual light sources and a deflection device that adjusts time intervals between scanning start times based on environmental changes, using line synchronization detection to ensure accurate color overlay by controlling the emission of light beams to first and second photosensitive members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the printer uses fixed scanning timing control, then the device complexity is low, but the image stacking accuracy deteriorates under varying printing environments
Solution Approach 1:
The patent implements dynamic scanning timing control by continuously monitoring the actual rotation angle of the polygon mirror and adjusting the scanning start times of different color light beams in real-time. This dynamic adjustment mechanism allows the system to adapt to environmental changes (temperature, humidity) that affect the polygon mirror's rotation speed, thereby maintaining high image stacking accuracy without requiring overly complex predictive control systems.
Solution Approach 2:
The system employs feedback control by detecting the actual rotation angle of the polygon mirror and using this information to adjust the scanning timing. The controller receives feedback about the polygon mirror's rotational state and modifies the scanning start times accordingly, creating a closed-loop control system that maintains accuracy under varying environmental conditions while keeping the control mechanism relatively simple.
2Manufacturing precision
If the printer adjusts scanning timing frequently to maintain accuracy, then the image stacking accuracy is maintained, but the loss of time increases due to continuous adjustments
Solution Approach 1:
The system maintains continuous scanning operation by performing timing adjustments dynamically during the scanning process rather than stopping to recalibrate. The controller continuously monitors the polygon mirror's rotation angle and makes real-time timing adjustments, ensuring that the useful action of image formation continues without interruption while maintaining accuracy.
3Adaptability or versatility
If the printer uses simple timing control, then the device complexity is low, but the adaptability to environmental changes deteriorates
Solution Approach 1:
The system implements self-service adaptability by automatically detecting changes in the printing environment through monitoring the polygon mirror's rotation angle and autonomously adjusting the scanning timing without requiring external intervention or complex environmental sensors. The system serves itself by using the existing rotational feedback to adapt to environmental changes, maintaining high adaptability while keeping the control mechanism relatively simple.
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
Ensures accurate color overlay in varying printing conditions by adjusting scanning start times, maintaining high image quality despite environmental fluctuations.
Implementation Method 1
a deflection device for rotating and deflecting a light beam
Implementation Method 2
the first photosensitive element is configured to sense the first light beam rotationally deflected by deflection device and generate a first detection signal
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The disclosure provides a laser scanning unit and a scanning control method, where the laser scanning unit includes a deflection device, an optical system, a first light source, a second light source, a line synchronization detection unit and a controller. The controller is configured to adjust a first time interval and/or a second time interval according to a change value of a third time interval. The first time interval is a time interval between a start time of a first detection signal and a first scanning start time, the second time interval is a time interval between a start time of a second detection signal and a second scanning start time, and the third time interval is a time interval between the start time of the first detection signal and the end time of the second detection signal.