Light Mixing Chamber for Uniform Document Illumination
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Solution Overview
Problem
Conventional illumination systems for document scanners often result in non-uniform illumination, leading to distorted images due to external light sources and internal reflections, and existing solutions for uniform illumination are either ineffective or too large for portable devices.
Innovation Solution
A compact light mixing chamber with a rectangular 6-faced polyhedron housing, featuring transparent glass sheets and strategically positioned light sources at a large incident angle, along with optional mirrors and diffusive materials, to minimize direct light entry into the camera and enhance uniform illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a closed illumination chamber is used to achieve uniform illumination, then illumination uniformity is improved, but device size increases
Solution Approach 1:
The light mixing chamber is nested within the scanner housing, with the light source positioned inside the chamber. The chamber itself is integrated into the existing scanner structure, allowing the illumination system to be compact while maintaining uniform lighting through the nested arrangement of components
Solution Approach 2:
The patent positions the light source at a large incident angle relative to the document surface, utilizing angular dimension rather than just linear distance. This allows the light to travel through the transparent glass sheet and mix uniformly across the document area without requiring a large linear chamber volume
2Illumination intensity
If light sources are positioned to illuminate the document, then illumination is provided, but hot spots are formed due to direct light reflection
Solution Approach 1:
A transparent glass sheet is introduced as an intermediary between the light source and the document. The glass sheet diffuses and scatters the direct light rays, preventing hot spots while still allowing sufficient illumination to reach the document surface for clear scanning
Solution Approach 2:
The patent employs a light mixing chamber with curved or angled surfaces that scatter and redistribute light rays in multiple directions. This curvature causes light to reflect and refract at various angles, eliminating concentrated hot spots and creating uniform illumination across the document
3Illumination intensity
If external light sources are present, then ambient illumination is provided, but uncontrolled reflections distort the scanned image
Solution Approach 1:
The patent extracts and isolates the illumination function within a dedicated light mixing chamber that is optically separated from the external environment. The chamber's transparent glass sheet and internal light mixing mechanisms control all light paths, excluding uncontrolled external reflections while maintaining necessary illumination
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 provides a small, efficient illumination system that significantly reduces hot spots and ensures substantially uniform illumination, improving image quality by minimizing external light interference and internal reflections.
Implementation Method 1
As light wave 20 moves through the medium having a refractive index n1 and hits the medium having a refractive index n2 at an angle of incidence θi
Implementation Method 2
Part of the wave light energy reflects back at an angle θr, whereas θr=θi, forming light wave 22
Implementation Method 3
at least one light source disposed inside the housing
Data Source
AI summary
An illumination chamber for illuminating an object with substantially uniform illumination and providing an image of the object, the illumination chamber includes a generally 6-faced polyhedron opaque housing, which encloses a light mixing chamber. The housing includes an object transparent glass sheet, an image transparent glass sheet and at least one light source disposed inside the housing. The object transparent glass sheet is disposed at a first of the two larger faces of the 6-faced polyhedron and image transparent glass sheet is disposed at the second large face of the 6-faced polyhedron, opposing the object glass sheet. The object to be imaged, typically a document, is disposed immediately adjacent to the external surface of the object transparent glass sheet. The image of the objects exits the housing through the image transparent glass sheet.