Optical Scanning Apparatus Beam Misalignment Correction
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Solution Overview
Problem
Existing optical scanning systems in image forming apparatuses face challenges in accurately correcting beam spot misalignment due to wavelength differences and mechanical errors, which are not adequately addressed by previous methods that ignore the presence of fθ lenses and polygon mirrors, leading to suboptimal print quality and increased costs from requiring measurement apparatuses on all devices.
Innovation Solution
An optical scanning apparatus that measures and corrects beam misalignment by using a holding unit to store data on beam misalignment, incorporating a light source, optical lens, and rotating polygon mirror, allowing for precise light emission control by measuring the main scanning direction misalignment with an external measurement apparatus, reducing the need for measurement mechanisms on each image forming apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If misalignment is corrected without consideration of fθ lens or polygon mirror, then correction process is simplified, but misalignment correction accuracy deteriorates
Solution Approach 1:
The patent performs misalignment measurement and correction data acquisition in advance, before the optical scanning apparatus is incorporated into the image forming apparatus. A holding unit stores the correction data, which is then applied during operation. This preliminary action resolves the contradiction by preparing correction data offline (simplifying the operational process) while ensuring high accuracy through comprehensive measurement that considers all optical components including fθ lens and polygon mirror.
2Measurement precision
If measurement apparatus is mounted on all image forming apparatuses, then misalignment measurement accuracy is improved, but device cost increases
Solution Approach 1:
The patent extracts the measurement function from the final image forming apparatus and performs it separately using an external measurement apparatus during the optical scanning apparatus testing phase. The correction data obtained is stored in a holding unit and transferred to the image forming apparatus. This extraction resolves the contradiction by achieving high measurement accuracy without requiring expensive measurement apparatuses to be integrated into every image forming apparatus.
3Measurement precision
If misalignment measurement is performed on image forming apparatus, then correction accuracy is improved, but system downtime increases
Solution Approach 1:
The patent performs misalignment measurement and correction data acquisition in advance, before the optical scanning apparatus is incorporated into the image forming apparatus. The correction data is stored in a holding unit and applied during operation without requiring additional measurement time. This preliminary action resolves the contradiction by achieving high correction accuracy while eliminating measurement-related downtime in the deployed system.
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 more accurate correction of beam misalignment, improving print quality and reducing downtime by allowing for off-line measurement and data storage of correction values, thus eliminating the need for costly measurement apparatuses on every device.
Implementation Method 1
an optical lens for converting the multiple beams to parallel lights
Implementation Method 2
a rotating polygon mirror for rotary-deflecting the multiple beams
Data Source
AI summary
Data concerning misalignment of beams is measured and held in an optical scanning apparatus before the optical scanning apparatus is incorporated in an image forming apparatus. The optical scanning apparatus includes a light source for emitting multiple beams, an optical lens for converting the multiple beams to parallel lights and a rotating polygon mirror for rotary-deflecting the multiple beams. Furthermore, the measurement apparatus measures main scanning direction misalignment among the multiple beams on a photosensitive member provided for the image forming apparatus, which has been determined by detecting the multiple beams from the rotating polygon mirror (and an fθ lens). The optical scanning apparatus includes a holding unit for holding the data concerning misalignment. The image forming apparatus in which the optical scanning apparatus is incorporated corrects the misalignment with the use of the data concerning misalignment inputted directly or indirectly from the holding unit.