Optical Reading Path With Diffusion Plate for Uniform Light Reception

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Solution Overview

Problem

Existing document reading apparatuses face issues with reduced light reception and uneven light distribution due to light scattering from the end surface of the light guide body, which affects the detection of document tilt angles and dust on the transparent plate.

Innovation Solution

The optical device incorporates a mirror surface reflecting plate with a diffusion plate that includes a backing coat layer and a light diffusion layer, configured to reduce light scattering and enhance light reception, and a lens unit to guide light to the light receiving unit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a scatterer is disposed in the light guide body to scatter light from the end surface, then light distribution is improved, but the amount of light received by the light receiving unit decreases

Engineering Contradiction:
Improvelight distributionVSAvoidamount of light
Core Design Contradiction:
Illumination intensityVSQuantity of substance

Solution Approach 1:

The patent introduces a diffusion plate as an intermediary component between the light guide body and the light receiving unit. This diffusion plate receives the scattered light from the light guide body and redistributes it, ensuring that sufficient light reaches the light receiving unit while maintaining improved light distribution characteristics.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The optical system is segmented into distinct functional components: the light guide body for light generation, the scatterer for light distribution, and the diffusion plate for light redistribution. This segmentation allows each component to optimize its specific function while working together to resolve the contradiction between light distribution and light quantity.

Inventive Principle:
Principle #1Segmentation

2Quantity of substance

If the amount of light is increased by adjusting the scatterer, then light reception is improved, but uneven amounts of light received by the light receiving unit occur

Engineering Contradiction:
Improveamount of lightVSAvoiduniformity of light distribution
Core Design Contradiction:
Quantity of substanceVSManufacturing precision

Solution Approach 1:

The diffusion plate serves as a mediator that receives uneven light distribution from the scatterer and transforms it into uniform light distribution. This intermediary component effectively decouples the light generation function from the light distribution function, allowing the scatterer to maximize light quantity while the diffusion plate ensures uniformity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The diffusion plate changes the optical parameters of the light, transforming the directional and uneven light from the scatterer into diffuse and uniform light. This parameter change in light distribution characteristics resolves the contradiction between light quantity and uniformity.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If a mirror surface reflecting plate is used to reflect light, then light reception efficiency is improved, but focal depth issues affect the light receiving unit

Engineering Contradiction:
Improvelight reception efficiencyVSAvoidfocal depth
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The diffusion plate acts as an intermediary between the mirror surface reflecting plate and the light receiving unit. It receives the reflected light and redistributes it uniformly, preventing the light receiving unit from being positioned within the focal depth of the lens unit while maintaining high light reception efficiency.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 increases the light reception and reduces uneven light distribution, enabling accurate detection of document tilt angles and effective dust correction, thereby improving the performance of the document reading apparatus.

Implementation Method 1

a light guide body that scatters light incident from an end surface with a scatterer disposed in a direction in which a side surface extends and emits the light

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 2

a mirror surface reflecting plate that mirror-reflects the light emitted from the light guide body

Methodology Applied
Scientific EffectMirror reflection: Reflection

Implementation Method 3

a diffusion plate that diffuses and transmits the light emitted from the light guide body and emits the light onto the mirror surface reflecting plate

Methodology Applied
Scientific EffectLight diffusion: Diffusion

Implementation Method 4

diffuses and transmits the light reflected by the mirror surface reflecting plate and emits the light to the light receiving unit

Methodology Applied
Scientific EffectLight diffusion: Diffusion

Data Source

PatentEP4498668B1Optical device and document reading apparatus
Publication Date: 2025.12.31 FUJIFILM BUSINESS INNOVATION CORP
  • EP4498668B1 patent drawingFigure 1
  • EP4498668B1 patent drawingFigure 2
  • EP4498668B1 patent drawingFigure 3

AI summary

An optical device includes: a light guide body that scatters light incident from an end surface with a scatterer disposed in a direction in which a side surface extends and emits the light; a mirror surface reflecting plate that mirror-reflects the light emitted from the light guide body; a light receiving unit that receives the light reflected by the mirror surface reflecting plate; and a diffusion plate that diffuses and transmits the light emitted from the light guide body and emits the light onto the mirror surface reflecting plate, and diffuses and transmits the light reflected by the mirror surface reflecting plate and emits the light to the light receiving unit.