Light Scanning Device Non-Parallel Package Surfaces

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Solution Overview

Problem

Existing image forming apparatuses using MEMS mirrors suffer from stray light reflection on glass windows, leading to unnecessary bright points in the image and increased package size and manufacturing costs due to the need for anti-reflection films and window inclinations.

Innovation Solution

A light scanning device with a package having two non-parallel light transmission surfaces, one for light incidence and one for extraction, eliminating the need for window inclinations and reducing package size and costs while maintaining stray light exclusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the glass window is inclined to guide reflected light outside the drawing region, then stray light is suppressed, but package size is increased due to increased thickness

Engineering Contradiction:
Improvestray lightVSAvoidpackage size
Core Design Contradiction:
Object-affected harmful factorsVSVolume of stationary object

Solution Approach 1:

The light transmission surface is segmented into multiple surfaces (first light transmission surface and second light transmission surface) that are not in the same plane. This segmentation allows the package to guide light through a multi-surface path rather than requiring a single inclined surface, thereby suppressing stray light while maintaining a compact overall structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from a two-dimensional planar light transmission surface to a three-dimensional multi-surface configuration. By arranging light transmission surfaces in different planes and orientations, the package effectively guides light through additional spatial dimensions, eliminating the need for a single thick inclined surface while still suppressing stray light.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If anti-reflection film is applied on the glass window surface to suppress reflected light, then stray light is reduced, but manufacturing cost is increased

Engineering Contradiction:
Improvereflected lightVSAvoidmanufacturing cost
Core Design Contradiction:
Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent extracts the light suppression function from the glass window surface itself and implements it through the geometric configuration of multiple light transmission surfaces. By taking out the need for anti-reflection coating and replacing it with a structural solution, the manufacturing cost is reduced while still achieving stray light suppression.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the optical coating approach (anti-reflection film) with a mechanical/structural approach (multi-surface geometry). By substituting the optical property modification with a structural light guiding path, the solution eliminates the need for expensive anti-reflection coating processes while achieving the same stray light suppression effect.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Object-affected harmful factors

If anti-reflection film is applied to completely suppress reflected light, then stray light is eliminated, but manufacturing complexity and cost are increased

Engineering Contradiction:
Improvereflected lightVSAvoidmanufacturing process complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent employs standard glass windows with conventional coating processes rather than requiring specialized anti-reflection coatings. By using readily available, standard manufacturing processes for the light transmission surfaces, the solution reduces manufacturing complexity and cost while achieving adequate stray light suppression through the multi-surface geometry.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 compact image forming apparatus that prevents stray light from entering the drawing region, reducing manufacturing costs and package size without compromising performance.

Implementation Method 1

a part of the laser light incident on the glass window may be reflected on a surface of the glass window

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 2

laser light is incident on the mirror device from an outside through a glass window provided in the package

Methodology Applied
Scientific EffectLight transmission: Refraction

Implementation Method 3

The mirror device is accommodated in a package in which a vacuum or a negative pressure is created in order to decrease air resistance of the swinging movable mirror

Methodology Applied
Scientific EffectAir resistance reduction through vacuum: Vacuum

Data Source

PatentEP4102286B1Light scanning device and image forming apparatus
Publication Date: 2025.06.25 FUJIFILM CORP
  • EP4102286B1 patent drawingFigure 1
  • EP4102286B1 patent drawingFigure 2
  • EP4102286B1 patent drawingFigure 3~4

AI summary

A light scanning device and an image forming apparatus that can be provided in a small size at a decreased manufacturing cost without causing stray light to be incident on a drawing region are provided. A light scanning device includes a mirror device that includes a movable mirror which swings about at least one axis, and a package that has at least two or more light transmission surfaces not constituting the same plane and accommodates the mirror device, in which out of the two or more light transmission surfaces of the package, one light transmission surface is a light receiving surface for receiving an incidence ray on the movable mirror from an outside, and the other light transmission surface is a light extraction surface for extracting light reflected by the movable mirror to the outside.