Erecting Equal-Magnification Lens Array Plate Stray Light Shielding

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Solution Overview

Problem

Erecting equal-magnification lens array plates in image reading devices suffer from bright and dark linear noise due to stray light, which degrades image quality, especially when documents are black or not present.

Innovation Solution

Incorporating a light-shielding wall on the light-shielding member facing the document table, positioned to shield light reflected by the document table, while ensuring it does not obstruct the light path that contributes to imaging, thereby reducing flare noise and linear noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a light shielding member is provided on the erecting equal-magnification lens array plate to remove stray light, then ghost noise is reduced, but bright and dark linear noise appears due to light reflected by the document table boundary surface

Engineering Contradiction:

Improveghost noiseVSAvoidbright and dark linear noise

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The light shielding member is segmented into multiple functional regions: a first light shielding region with through holes to block diagonal stray light (reducing ghost), and a second light shielding region without through holes to block reflected light from the document table (reducing linear noise). This segmentation allows each region to address specific noise sources independently.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the light shielding member have different optical properties: the first light shielding region has through holes aligned with lenses to allow imaging light through while blocking stray light, whereas the second light shielding region is solid to block reflected light. This local differentiation of structure and function enables targeted noise reduction in different areas.

Inventive Principle:

Principle #3Local quality

2Reliability

If the number of columns of rod lenses is increased to improve light transmission proportion, then unevenness in light transmitted is reduced, but manufacturing cost increases

Engineering Contradiction:

Improvelight transmission uniformityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of using multiple columns of individual rod lenses which increases cost, the patent uses a single lens array plate with micro-convex lenses formed by injection molding. This copying approach replicates the optical function of multiple rod lens columns using a more cost-effective manufacturing process while achieving similar light transmission uniformity.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent replaces the mechanical assembly of multiple rod lens columns with a single integrated lens array plate formed by injection molding. This substitution of manufacturing method reduces assembly complexity and cost while maintaining the optical performance of multiple lens columns through the molded structure design.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 reduces bright and dark linear noise, enhancing image quality by blocking stray light without impairing the imaging process, resulting in a high-quality image with minimized noise artifacts.

Implementation Method 1

light reflected by the boundary surface of the document table

Methodology Applied

Scientific EffectLight reflection: Reflection

Implementation Method 2

light-shielding wall provided upright on a surface of the light-shielding member facing the document table and configured to shield light reflected by the document table

Methodology Applied

Scientific EffectLight shielding: Absorption (EM radiation)

Implementation Method 3

erecting equal-magnification lens array plate configured to receive light emitted by a line light source and reflected from a document placed on a document table, and form an erect equal-magnification image on a light receiving surface of a line image sensor

Methodology Applied

Scientific EffectLight refraction: Refraction

Data Source

PatentUS8947747B2Erecting equal-magnification lens array plate and image reading device

Publication Date: 2015.02.03 NIPPON SHEET GLASS CO LTD

AI summary

An image reading device includes: a document table on which a document G is placed; a line light source configured to illuminate the document G; an erecting equal-magnification lens array plate configured to receive light reflected from the document G and form an erect equal-magnification image on a predetermined image plane; and a line image sensor configured to receive the erect equal-magnification image formed by the erecting equal-magnification lens array plate. The erecting equal-magnification lens array plate includes: first and second lens array plates formed with a plurality of lenses on both sides thereof; a first shielding member provided on the first outer side surface of the first lens array plate; and a light-shielding wall provided upright on the top surface of the first light-shielding member and configured to shield light reflected by the document table.