Multi-Beam Optical Scanning Apertures for Uniform Beam Intervals
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Solution Overview
Problem
Existing optical scanning apparatuses with multi-beam systems suffer from image defects due to angular misalignment of the polygon mirror, causing uneven intervals between imaged light beams and color displacement, while maintaining low manufacturing costs is a challenge.
Innovation Solution
The optical scanning apparatus includes a light source with multiple light-emitting portions, a cylindrical lens, a restricting portion with movable apertures, and scanning lenses, where the apertures adjust the optical path width to stabilize beam intervals by displacing the imaged positions of light beams along the sub scanning direction, and reversing their movement directions at the ends of the scanned surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the polygon mirror rotates to scan light beams, then the scanned surface is scanned along the main scanning direction, but angular misalignment of the rotation axis causes uneven intervals between imaged light beams along the sub scanning direction
Solution Approach 1:
The patent changes the position parameters of the light sources and apertures along the sub scanning direction to compensate for angular misalignment. By adjusting the relative positions of light sources and corresponding apertures, the system corrects the uneven beam intervals caused by polygon mirror misalignment while maintaining high scanning speed.
Solution Approach 2:
The patent introduces asymmetric positioning of apertures relative to light sources, where each aperture is offset by a specific distance from the optical axis in the sub scanning direction. This asymmetric arrangement compensates for the symmetric error introduced by angular misalignment of the polygon mirror rotation axis.
2Productivity
If multiple light sources are used to form multi-beam system, then productivity increases, but manufacturing cost increases
Solution Approach 1:
The patent makes a single polygon mirror serve multiple functions by using it to scan light beams from multiple light sources simultaneously. The shared optical path and common scanning mechanism reduce the number of components needed, lowering manufacturing cost while maintaining high productivity through multi-beam operation.
Solution Approach 2:
The patent merges multiple optical paths into a single scanning system where multiple light sources share common optical components including the polygon mirror and scanning lenses. This consolidation reduces component count and manufacturing complexity while achieving efficient multi-beam scanning.
3Manufacturing precision
If scanning lenses with non-spherical coefficients are used, then scanning line curvature is suppressed, but device complexity increases
Solution Approach 1:
The patent applies local quality correction by positioning apertures at specific locations to correct scanning line curvature in critical areas. Rather than using complex non-spherical lenses throughout the system, the aperture positioning provides localized correction where it is most needed, simplifying the overall lens design.
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 ensures even intervals between imaged light beams, preventing image defects and maintaining image quality while reducing manufacturing costs by minimizing component count.
Implementation Method 1
The cylindrical lens converges the light beams emitted from the light-emitting portions
Implementation Method 2
The polygon mirror has a deflecting surface that reflects the light beams having passed through the cylindrical lens
Data Source
AI summary
An optical scanning apparatus includes a light source having five or more light-emitting portions arrayed in a row, a cylindrical lens, a restricting portion, a polygon mirror, and a plurality of scanning lenses. A plurality of such light sources are provided and each emit light beams. The restricting portion has a plurality of first apertures that restrict the optical path width of the light beams along the sub scanning direction. The first apertures have first openings respectively that penetrate them along the optical axis direction and let the light beams pass through them. The centers of the first openings along the sub scanning direction are disposed displaced along the sub scanning direction.