Segmented Light Guide Illumination Uniformity

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing illumination devices face issues such as the generation of image stripes due to protruding/recessed light diffusing portions near the light source and reduced total illuminance when diffusing lines are formed along the entire length of the light guide member.

Innovation Solution

The illumination device features a light guide member with a first light diffusing portion near the light source and a second light diffusing portion with lower diffusivity adjacent to the first, both having protruding/recessed shapes, to suppress image stripe generation without reducing illuminance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a protruding/recessed portion for diffusing light is formed in a part near the light source, then the peak of illuminance distribution is removed and illuminance can be made uniform, but stripes (image stripes) may be generated in a scanned image at the boundary position

Engineering Contradiction:

Improveuniformity of illuminance distributionVSAvoidimage stripes in scanned image

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The light diffusing portion is divided into multiple segments along the longitudinal direction of the light guide member. Each segment has different light diffusing characteristics, allowing the illuminance distribution to be controlled in stages without creating sharp boundaries that would cause image stripes.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the light guide member are given different light diffusing properties. The first light diffusing portion has higher light diffusing capability than the second light diffusing portion, creating localized quality variations that control illuminance distribution while avoiding uniform patterns that cause stripes.

Inventive Principle:

Principle #3Local quality

2Illumination intensity

If protruding/recessed lines are formed along the entire length of the light emission surface, then illuminance distribution can be maintained within a predetermined range, but the total illuminance on an object is reduced

Engineering Contradiction:

Improveuniformity of illuminance distributionVSAvoidtotal illuminance on object

Core Design Contradiction:

Illumination intensityVSQuantity of substance

Solution Approach 1:

Light diffusing portions are formed only in specific regions (first and second light diffusing portions) rather than along the entire length of the light emission surface. This partial action approach maintains illuminance uniformity where needed while preserving total illuminance by avoiding excessive light diffusion throughout the entire structure.

Inventive Principle:

Principle #16Partial or excessive action

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 ensures uniform illuminance along the light guide member's length, preventing image stripe formation while maintaining overall illuminance levels.

Implementation Method 1

a light guide member that is made of a transparent material and that has a bar-like shape; and a light source that is disposed so as to face at least one end surface of the light guide member. The illumination device guides light from the light source in the light guide member and emits the light from a light emission surface of the light guide member

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

The light emission surface includes a first light diffusing portion that is formed in a first portion of the light emission surface near the light source and that has a protruding/recessed shape and a second light diffusing portion that is formed in a second portion of the light emission surface adjacent to an end of the first light diffusing portion

Methodology Applied

Scientific EffectLight diffusion: Scattering

Data Source

PatentUS10567609B2Illumination device, image scanning apparatus, and image forming apparatus

Publication Date: 2020.02.18 SHARP KK

AI summary

An illumination device includes a light guide member having a bar-like shape and a light source disposed so as to face an end surface of the light guide member. The illumination device guides light from the light source in the light guide member and emits the light from a light emission surface of the light guide member formed in a longitudinal direction of the light guide member. The light emission surface includes a first light diffusing portion that is formed in a first portion near the light source and that has a protruding/recessed shape, and a second light diffusing portion that is formed in a second portion adjacent to an end of the first light diffusing portion, the end being away from the light source. The second light diffusing portion has a protruding/recessed shape and has lower light diffusivity than the first light diffusing portion.