Optical Beam Scanning Gate Positioning for Residual Strain Control
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Solution Overview
Problem
Conventional optical beam scanning systems face challenges in maintaining image quality and reducing scattering due to residual strain or deformation in lens molding, especially in overillumination scanning systems where the beam diameter varies with scanning position, leading to asymmetric optical characteristics and increased manufacturing costs.
Innovation Solution
An optical beam scanning apparatus with a pre-deflection optical system that forms a luminous flux wider than the reflecting surface, and a post-deflection optical system with a resin molding die that positions the gate opening on the light incidence side to minimize residual strain and deformation, ensuring uniform beam diameter and improved image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the beam width is increased to cover the entire reflecting surface (overillumination), then the beam diameter on the image surface becomes larger, but scattering increases and image quality deteriorates
Solution Approach 1:
The patent applies local quality by positioning the gate opening specifically on the light incidence side of the lens, creating a localized region with minimized residual strain. This selective positioning ensures that the area most critical for optical performance (where the laser beam enters) has superior optical characteristics, while other regions of the lens may have different properties. This resolves the contradiction by improving beam diameter uniformity in the critical region without requiring a reduction in overall beam width.
2Ease of manufacture
If resin molding is used to reduce manufacturing costs, then production efficiency increases, but residual strain and deformation occur affecting optical characteristics
Solution Approach 1:
The patent applies preliminary action by strategically positioning the gate opening on the light incidence side before the molding process begins. This pre-planned positioning ensures that the region where the laser beam enters the lens has minimized residual strain from the molding process. By preparing the mold design in advance with the gate opening in the optimal location, the patent prevents optical characteristic deterioration rather than attempting to correct it after molding, thus maintaining both low manufacturing cost and high optical precision.
3Ease of manufacture
If the gate opening is positioned on the opposite side to light incidence, then manufacturing is simplified, but residual strain causes increased scattering and beam diameter variation
Solution Approach 1:
The patent applies inversion by reversing the conventional gate opening positioning approach. Instead of placing the gate opening on the opposite side to light incidence (conventional practice), the patent positions it on the light incidence side. This inverted approach initially seems counterintuitive but actually reduces residual strain in the critical optical path, thereby decreasing scattering and beam diameter variation. This resolves the contradiction by showing that the conventional wisdom about gate positioning needs to be inverted for optical lenses subjected to laser irradiation.
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 reduces scattering and maintains high image quality by ensuring consistent beam diameter and optical characteristics across the scanning region, while also lowering manufacturing costs by reducing the need for additional noise reduction elements.
Implementation Method 1
a pre-deflection optical system for forming a luminous flux emitted from the light source to image the luminous flux as a line image in a prescribed direction corresponding to a main scanning direction
Implementation Method 2
a scanning unit for scanning the imaged luminous flux by the pre-deflection optical system against a scanning subject
Implementation Method 3
a post-deflection optical system for imaging the luminous flux scanned by the scanning unit on the scanning subject
Data Source
AI summary
In an image forming apparatus according to the invention, an optical beam scanning apparatus of an overillumination scanning optical system includes a laser, a pre-deflection optical system, a polygon mirror, and a post-deflection optical system, wherein the post-deflection optical system includes at least one optical element configured by allowing a resin to flow into a molding die through a gate opening provided in advance to the molding die and then molding the resin into a prescribed shape; and in the optical element, a side corresponding to aside of the gate opening through which the resin flows is provided to a light incidence side where the luminous flux enters into the polygon mirror.