Optical Scanning Device Beam Synchronization
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Solution Overview
Problem
Existing optical scanning devices in electrophotographic image forming apparatuses face challenges in synchronizing light beams accurately across the image writing start and end positions, leading to potential deviations in image formation.
Innovation Solution
The optical scanning device incorporates a plurality of light sources, photodetectors, optical element groups, and a polygon mirror to deflect light beams in the main scanning direction. The device includes specific optical element groups that are rotationally symmetrical and cross a rotation axis parallel to the main scanning direction, ensuring precise beam synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single photodetector is used to detect beams at image writing start and end positions, then the device structure is simple, but beam synchronization precision deteriorates due to inability to detect multiple beam positions simultaneously
Solution Approach 1:
The patent divides the detection function into multiple photodetectors positioned at different locations (image writing start position and end position). Each photodetector independently detects beam positions, enabling simultaneous multi-point measurement without requiring a single complex detector system.
Solution Approach 2:
The patent introduces optical element groups (including mirrors and lenses) as intermediaries to guide and direct beams from different positions to the photodetectors. These optical elements enable precise beam routing and positioning without requiring direct line-of-sight between beams and detectors.
2Measurement precision
If optical elements are added to guide beams to photodetectors, then beam detection precision improves, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The optical element groups serve multiple functions: they guide beams from different positions, focus beams onto photodetector surfaces, and maintain beam synchronization. This multi-functionality reduces the need for separate components for each function, simplifying overall device manufacturing.
Solution Approach 2:
The patent positions optical elements and photodetectors to create symmetrical optical paths with equal optical lengths from the polygon mirror to each detection point. This equipotential design ensures that beam synchronization is maintained without requiring complex active adjustment mechanisms.
3Measurement precision
If multiple photodetectors are positioned at different locations, then beam position detection accuracy improves, but alignment and calibration difficulty increases
Solution Approach 1:
The optical element groups are configured to create equal optical path lengths from the polygon mirror to each photodetector. This symmetrical arrangement ensures that all detection points are on an equal footing, simplifying calibration by eliminating path length differences as a variable.
Solution Approach 2:
The photodetectors provide real-time feedback on beam positions at different locations. This feedback is used to adjust and maintain proper alignment of the optical elements and polygon mirror, enabling continuous calibration and compensation for any drift or misalignment.
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 configuration enables accurate detection of beam positions at the start and end of the image writing process, allowing for precise synchronization and minimizing image deviations, thus enhancing the overall image forming process.
Implementation Method 1
The optical scanning device includes, for example, photodetectors that detect a plurality of beams
Implementation Method 2
The polygon mirror deflects the beams for scanning in one direction of the main scanning direction from one end to the other end
Data Source
AI summary
An optical scanning device deflects light for scanning in a main scanning direction and includes a plurality of light sources, a plurality of photodetectors, a plurality of optical element groups, and a polygon mirror. The plurality of light sources emit laser lights. The plurality of photodetectors detect beams formed by the laser lights. The plurality of optical element groups guide the beams to the photodetectors. The polygon mirror deflects the beams for scanning in one direction of the main scanning direction from one end to the other end on the opposite side of the one end. The plurality of optical element groups cross a crossing axis parallel to the main scanning direction, cross a rotation axis of the polygon mirror, and are rotationally symmetrical with respect to an axis of symmetry parallel to the rotation axis of the polygon mirror.