Diffusing Member Protrusion Angles Reduce Image Stripes
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Solution Overview
Problem
Conventional image reading devices experience illuminance unevenness and density issues due to light source spacing, leading to light and dark stripes in images, especially when scanning glossy or thick originals, and increasing diffusivity to mitigate these issues reduces light intensity on the original.
Innovation Solution
A diffusing member with a specific protruding portion structure on its surface, where the protruding portions are arranged in a particular pattern to enhance light diffusivity while minimizing light loss, characterized by specific frequency ratios of inclination angles to optimize light distribution and reduce light and dark stripes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the fine structure on the exit surface of the light guiding body is changed to increase diffusivity, then light and dark stripes are reduced, but light amount incident on the original is reduced
Solution Approach 1:
The patent applies parameter changes by precisely controlling the inclination angles of protruding portions on the diffusing surface. Specifically, it defines frequency ratios between different inclination angle ranges (β/α and γ/β) to optimize light diffusion while preserving sufficient light intensity. This quantitative parameter control allows the structure to diffuse light effectively without excessive light loss through total internal reflection.
Solution Approach 2:
The patent implements local quality by creating protruding portions with specific inclination angles at different locations on the diffusing surface. The structure varies the local surface properties through controlled inclination angle distributions, where certain regions have steeper angles for enhanced diffusion while other regions maintain gentler angles to preserve light transmission, thereby achieving spatially optimized light distribution.
2Device complexity
If light sources are spaced away from each other, then illuminating device structure is simplified, but illuminance unevenness is generated
Solution Approach 1:
The patent introduces a diffusing member as an intermediary component between the spaced light sources and the original. This diffusing member receives light from multiple spaced light sources and redistributes it uniformly across the original surface, thereby mediating the illumination to eliminate unevenness while preserving the structural simplicity of spaced light source arrangement.
Solution Approach 2:
The patent applies segmentation by dividing the illumination function into multiple components: separate light sources for illumination and a dedicated diffusing member for uniform distribution. This functional segmentation allows the light sources to be spaced apart for structural simplicity while the diffusing member handles the uniformity requirement through its controlled protruding portion structure.
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 effectively improves light diffusivity without decreasing the light amount on the original, thereby reducing the formation of light and dark stripes in the read image, ensuring better image quality.
Implementation Method 1
ω represents a radiation angle of the light incident on the diffusing surface, and n represents a refractive index of the diffusing member
Implementation Method 2
a light amount of light totally reflected by the fine structure may be increased
Data Source
AI summary
The diffusing member includes a diffusing surface with protruding portions arrayed in a first direction. The protruding portions include a first group of protruding portions in which tops thereof are arranged on a first line parallel to the first direction when they are projected on a first cross section parallel to the first direction. Frequencies of inclination angles of the first group of protruding portions α within a range of 0°±5°, β within a range of[sin-1(1n)+12sin-1(sin ωn)]±5° and-[sin-1(1n)+12sin-1(sin ωn)]±5°,and γ within a range of[sin-1(1n)+12sin-1(sin ωn)]±5° and-[sin-1(1n)+12sin-1(sin ωn)]±5°,at respective positions on a predetermined line parallel to the first direction of the first group when the first group is projected on a second cross section including each top thereof and perpendicular to the first cross section, a radiation angle of light incident on the diffusing surface ω, and a refractive index of the diffusing member n, are appropriately set.