Optical Scanning Device Curved Light-Emitting Surface Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical scanning devices face challenges in achieving high-speed and high-density image formation due to issues like thermal crosstalk, optical characteristic instability, and increased cost associated with correcting refractive index variations, particularly when using multibeam writing systems and resin lenses.
Innovation Solution
The optical scanning device employs a light source with light emitting points arranged in concentric rings or a parallelogram pattern, coupled with a scanning optical system that includes a coupling optical element and a deflecting unit, ensuring that the condition F tan(θ/2)+A<D/0.7 is met, which reduces the effective diameter of the optical element and maintains optical efficiency while preventing diffraction and cost increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of light-emitting elements is increased to achieve high-density image formation, then the light-use efficiency and optical characteristics deteriorate because light emitting points are farther from the optical axis
Solution Approach 1:
The patent employs a curved (concave) light-emitting surface instead of a flat surface. This curvature allows light emitting points to be positioned closer to the optical axis while still achieving high light-emitting element density, thereby maintaining optical characteristics such as light-use efficiency and field curvature even when increasing the number of light-emitting elements for high-density image formation
2Reliability
If a diffractive optical surface is provided on the scanning lens to correct focus position variation, then manufacturing cost and machining time increase due to the wide area required for light flux passage
Solution Approach 1:
The patent extracts the diffractive optical surface from the scanning lens and relocates it to the light-emitting surface. This extraction allows the diffractive structure to be applied only to the necessary area for light generation rather than the entire wide scanning lens surface, significantly reducing manufacturing cost and machining time while still achieving focus position correction
Solution Approach 2:
The patent introduces a curved light-emitting surface with diffractive structure as an intermediary element between the light source and the scanning optical system. This intermediary serves dual functions: generating light beams and providing diffraction-based focus correction, eliminating the need for expensive wide-area diffractive machining on the scanning lens
3Manufacturing precision
If the curvature of lens surface is increased to reduce spot diameter, then diffraction occurs and light-use efficiency decreases
Solution Approach 1:
The patent uses a carefully optimized curved light-emitting surface that provides sufficient curvature to reduce spot diameter while controlling the degree of curvature to avoid excessive diffraction. The concave shape focuses light effectively without creating diffraction losses that would reduce light-use efficiency
Solution Approach 2:
The patent optimizes the curvature radius of the light-emitting surface as a critical parameter. By adjusting this parameter, the system achieves the right balance between spot diameter reduction (needing high curvature) and diffraction minimization (requiring moderate curvature), thereby maintaining both manufacturing precision and light-use efficiency
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 light-use efficiency, reduces manufacturing errors, and achieves stable high-density image formation with reduced thermal crosstalk and cost, while maintaining optical characteristics even at varying temperatures and wavelengths.
Implementation Method 1
a first coupling optical element that couples the light beams into a light flux
Implementation Method 2
a deflecting unit that deflects and scans the light flux
Implementation Method 3
a scanning optical system that focuses the light flux from the deflecting unit onto an imaging surface to form an image
Implementation Method 4
Japanese Patent Application Laid-Open Nos. 2004-126192 and 2005-258392 disclose a technology for reducing variation of a focus position due to temperature change by combining a diffractive surface and a refractive surface in an optical system provided in an upstream side of a deflector
Data Source
AI summary
An optical scanning device includes a light source having light emitting points for emitting light beams, a coupling optical element that couples the light beams, a deflecting unit that deflects and scans the light beams, and a scanning optical system that focus the light beams to form an image. The optical scanning device satisfies the following condition: F tan(theta/2)+A<D/0.7 where A is the maximum distance between the light emitting points and an optical axis of the coupling optical element, theta is a divergence angle (full-width half-maximum) of the light beams, F is a focal length of. the coupling optical element, and D is an effective radius of the coupling optical element.