Light Source Unit for Image Reading with Multi-Wavelength Irradiation

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Solution Overview

Problem

Existing image reading devices face challenges in achieving sufficient irradiation properties for both visible and non-visible light due to differences in refractive index, transmittance, and reflectance between visible and non-visible light wavelengths, leading to inadequate light distribution and intensity.

Innovation Solution

A light source unit comprising a light source emitting visible and non-visible light, a rod-like light guide with a linear reflecting layer, and support members with a second reflecting layer made of materials that have higher reflectivity for non-visible light wavelengths, ensuring efficient reflection and distribution of light across the spectrum.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single light guide is used for both visible and non-visible light, then the device structure is simplified, but the irradiation properties become insufficient due to different optical properties at different wavelengths

Engineering Contradiction:
Improvedevice structureVSAvoidirradiation properties
Core Design Contradiction:
Device complexityVSIllumination intensity

Solution Approach 1:

The patent divides the light guide system into multiple separate light guides, each optimized for specific wavelength ranges. This segmentation allows each light guide to have tailored optical properties (refractive index, transmittance, reflectance) for its designated wavelength range, thereby maintaining high irradiation properties while managing device complexity through functional specialization.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different portions of the optical system are assigned different properties based on wavelength requirements. Each light guide is designed with local quality optimized for its specific wavelength range, such as using materials with appropriate transmittance and refractive index characteristics for visible, ultraviolet, or infrared light respectively.

Inventive Principle:
Principle #3Local quality

2Illumination intensity

If multiple light guides are used for different wavelengths, then the irradiation properties for each wavelength are improved, but the device complexity increases

Engineering Contradiction:
Improveirradiation propertiesVSAvoiddevice structure
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent combines multiple light guides and their corresponding light sources into an integrated illumination device. By merging these components into a unified structure with coordinated optical paths, the device achieves improved irradiation properties across multiple wavelengths while controlling overall complexity through systematic integration rather than separate independent systems.

Inventive Principle:
Principle #5Merging (Combining)

3Illumination intensity

If standard reflecting materials are used, then the visible light reflectivity is high, but the non-visible light reflectivity is insufficient

Engineering Contradiction:
Improvenon-visible light reflectivityVSAvoidreflecting material selection
Core Design Contradiction:
Illumination intensityVSEase of manufacture

Solution Approach 1:

The patent employs composite reflecting materials that combine multiple substances with complementary reflectivity characteristics across different wavelength ranges. These composite materials maintain high reflectivity for both visible and non-visible light, achieving broad-spectrum performance while remaining manufacturable through conventional coating and material processing techniques.

Inventive Principle:
Principle #40Composite materials

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 enables effective irradiation properties for both visible and non-visible light, enhancing the accuracy and reliability of image reading devices in capturing images with invisible ink reflections or fluorescence.

Implementation Method 1

a reflecting layer that is linear along the long axis direction and provided on the contour surface of the light guide; and support members encompassing the reflecting layer and the light guide, having a second reflecting layer on a surface of an opening extending along the long axis direction of the support members; wherein the reflecting layer and the second reflecting layer of the support members are formed by a reflecting material containing a first reflecting substance that reflects visible light and light of a non-visible light wavelength

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP2800348B1Light source unit and image reading device
Publication Date: 2019.10.02 MITSUBISHI ELECTRIC CORP
  • EP2800348B1 patent drawingFigure 1
  • EP2800348B1 patent drawingFigure 2~4
  • EP2800348B1 patent drawingFigure 5

AI summary

The light source unit comprises a light source emitting visible light and light of a non-visible wavelength; a rod-like light guide (2) at the end of which the light source is provided and within which incident light from the light source is propagated in the long axis direction; a reflector that is linear along the long axis direction and provided on the contour surface of the light guide; and a support member (3) encompassing the reflector and light guide (2), having a given width in the direction perpendicular to the long axis direction, and provided with an opening extending along the long axis direction. The reflector and support member (3) are formed by a reflecting material containing a substance reflecting the light of a non-visible light wavelength and reflecting the visible light and light of a non-visible light wavelength.