Optical Beam Scanning Device Pre-Deflection System
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Solution Overview
Problem
Conventional optical beam scanning devices face challenges in maintaining uniform beam diameters and stabilizing optical characteristics when attempting to increase scanning speed, particularly in overfilled optical systems.
Innovation Solution
The optical beam scanning device incorporates a rotating deflector with multiple reflecting surfaces at specific tilt angles and a pre-deflection optical system that shapes the light beam to pass near the optical axis of the post-deflection system, allowing for efficient scanning and improved optical characteristics by using shared fθ lenses to control wave aberration and reduce component count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If an overfilled optical system is adopted to increase scanning speed, then scanning speed increases, but main scanning direction beam diameters become non-uniform and optical characteristics are not stabilized
Solution Approach 1:
The pre-deflection optical system performs preliminary shaping of the light beam before it enters the rotating deflector. By pre-shaping the beam to have a specific width in the main scanning direction and positioning it to pass through the optical axis of the post-deflection optical system, the system ensures uniform beam diameters and stable optical characteristics even when using an overfilled optical system for high-speed scanning.
2Speed
If an overfilled optical system is adopted to increase scanning speed, then scanning speed increases, but the number of optical components increases
Solution Approach 1:
The pre-deflection optical system and post-deflection optical system are merged into a coordinated configuration where the pre-deflection system shapes the beam and the post-deflection system guides it. This merging allows the use of an overfilled optical system for high-speed scanning while maintaining uniform beam diameters and stable optical characteristics, and enables sharing of fθ lenses between the two systems to reduce the total number of components.
3Reliability
If conventional optical paths are used, then optical characteristics are stable, but scanning speed cannot be increased
Solution Approach 1:
The pre-deflection optical system performs preliminary shaping of the light beam before it enters the rotating deflector. By pre-shaping the beam to have a specific width in the main scanning direction and positioning it to pass through the optical axis of the post-deflection optical system, the system ensures uniform beam diameters and stable optical characteristics even when using an overfilled optical system for high-speed scanning.
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 enhances scanning speed, stabilizes optical characteristics, reduces the number of optical components, and prevents deterioration in image quality, while allowing for a more compact and cost-effective image forming apparatus.
Implementation Method 1
a rotating deflector that reflects and deflects an incident light beam with plural reflecting surfaces arrayed in association with the respective plural photoconductive members in a rotating direction
Data Source
AI summary
An optical beam scanning device includes a polygon mirror 80 in which tilt angles with respect to a rotation axis of the polygon mirror 80 of respective plural reflecting surfaces are set to angles corresponding to photoconductive members associated with the respective reflecting surfaces, a post-deflection optical system A1 that guides light beams reflected and deflected by the respective plural reflecting surfaces in the polygon mirror 80 to the photoconductive surfaces of the photoconductive members corresponding to the respective reflecting surfaces, and a pre-deflection optical system 7a that shapes the light from the light source to be a light beam of a predetermined sectional shape and guides the light beam to the polygon mirror 80, the pre-deflection optical system 7a guiding the light from the light source to the polygon mirror 80 through an optical path that passes, in the main scanning direction, on an optical axis of the post-deflection optical system A1 and passes, in the sub-scanning direction, a position further apart from the optical axis of the post-deflection optical system A1 than all light beams after reflection and deflection guided by the post-deflection optical system A1.