Light Guide Diffusion Pattern for Uniform Illumination
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Solution Overview
Problem
Existing illuminators for image reading devices and electro-photographic image forming apparatuses face challenges in achieving uniform light distribution in both the main scanning and sub scanning directions, leading to potential deterioration in reading performance due to non-uniform light irradiation.
Innovation Solution
The proposed illuminator incorporates a light guide with a diffusion pattern on its emission face, featuring semi-cylindrical structures that extend from one end to the other, allowing for uniform or near-uniform light distribution. This light guide is designed to emit light uniformly in both the main and sub scanning directions, ensuring consistent light irradiation even with minor optical system misalignments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional light guide without diffusion pattern is used, then the structure is simple, but the light distribution is non-uniform leading to deterioration in reading performance
Solution Approach 1:
The light guide structure is designed with different properties in different regions: the emission face includes a diffusion pattern (protrusions or recesses) on the surface to scatter light uniformly, while the main body remains a simple light guide. This local modification achieves uniform light distribution without making the entire structure complex.
Solution Approach 2:
The diffusion pattern on the emission face utilizes curved surface features (protrusions or recesses) to scatter light in multiple directions. The curved geometry of the diffusion structures helps to randomize light paths and achieve more uniform light distribution across the emission surface.
2Manufacturing precision
If the light guide emits light uniformly in main scanning direction, then reading performance is improved, but sensitivity to sub scanning direction misalignment increases
Solution Approach 1:
The diffusion pattern is specifically applied to the emission face of the light guide, creating a localized scattering region. This allows the light guide to maintain its simple structure while adding the functional property of light scattering exactly where needed (at the emission point), thereby achieving both uniform light distribution and reduced sensitivity to misalignment.
Solution Approach 2:
The diffusion pattern acts as an intermediary element between the light guide and the document. It mediates the light by scattering it in multiple directions, which softens the directional nature of the light and reduces the impact of misalignment between the optical system components.
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
The solution ensures enhanced image reading performance by maintaining uniform light distribution across the document, preventing deterioration in reading quality due to minor positional displacements and improving the effectiveness of the charge eliminator in image forming apparatuses.
Implementation Method 1
a light guide to guide the light generated from the light source toward the document
Implementation Method 2
A diffusion pattern may be formed on the emission face to extend from one longitudinal end to the other longitudinal end of the emission face
Data Source
AI summary
An image forming apparatus employing an illuminator configured to irradiate light to a photosensitive body to change a level of electrical potential of the photosensitive body. The illuminator includes at least one light source configured to generate light and a light guide configured to guide the light received from the light source toward the photosensitive body. The light guide includes at least one incidence face and an emission face. The at least one incidence face faces the light source in a main scanning direction to receive the light from the light source into the light guide. The light exits from the light guide through the emission face toward the photosensitive body. The emission face includes a diffusion pattern having a plurality of semi-cylindrical structures along a width direction of the light guide. A radius of curvature of the semi-cylindrical structures increases away from the at least one light source.