Multi-Beam Light Scanning Layout for Compact Polygon Mirrors

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Solution Overview

Problem

Existing light scanning apparatuses face challenges in miniaturization in the rotation axis direction of a rotary polygon mirror due to the arrangement of multiple light sources, leading to increased size and potential image quality degradation.

Innovation Solution

The light scanning apparatus is designed with light sources arranged to have angular differences in both the main and sub-scanning directions, utilizing a compact housing configuration that minimizes the size of the apparatus while maintaining image quality by optimizing the placement of optical elements and mirrors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple light sources are arranged in parallel in the rotation axis direction of the rotary polygon mirror, then the multi-beam function is achieved, but the size of the light scanning apparatus increases in the rotation axis direction

Engineering Contradiction:
Improvemulti-beam functionVSAvoidsize in rotation axis direction
Core Design Contradiction:
Adaptability or versatilityVSLength of stationary object

Solution Approach 1:

The patent transitions from arranging light sources in the rotation axis direction (one dimension) to arranging them in the main scanning direction (another dimension). This dimensional change allows multiple light sources to be accommodated without increasing the apparatus size in the rotation axis direction, thereby resolving the technical contradiction between achieving multi-beam function and maintaining compact dimensions.

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

2Length of stationary object

If light sources are arranged with angular differences in main scanning direction, then compact housing configuration is achieved, but precise laser light alignment becomes more difficult

Engineering Contradiction:
Improvehousing sizeVSAvoidlaser light alignment precision
Core Design Contradiction:
Length of stationary objectVSManufacturing precision

Solution Approach 1:

The patent applies local quality by providing individual collimator lenses for each light source position. Each collimator lens is specifically positioned to collimate the laser light from its corresponding light source with the appropriate angular difference. This localized optical element arrangement enables precise laser light alignment despite the compact housing configuration with angular differences, resolving the contradiction between compactness and alignment precision.

Inventive Principle:
Principle #3Local quality

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 allows for a reduction in the overall size of the light scanning apparatus without compromising image quality, achieving a more compact design while ensuring precise laser light alignment and reduced surface eccentricity of the rotary polygon mirror.

Implementation Method 1

a light spot is formed on a surface of a photosensitive member by deflecting laser light emitted from a light source

Methodology Applied
Scientific EffectLight emission from semiconductor laser: Laser

Implementation Method 2

by deflecting laser light emitted from a light source using a rotary polygon mirror

Methodology Applied
Scientific EffectLight reflection and deflection by rotary polygon mirror: Reflection

Implementation Method 3

condensing them onto the photosensitive member using an imaging optical system

Methodology Applied
Scientific EffectLight condensation and focusing: Focusing

Implementation Method 4

The light spot scans on the surface on the photosensitive member so that a latent image is formed on the surface of the photosensitive member

Methodology Applied
Scientific EffectPhotoelectric exposure to form latent image: Photoelectric Effect

Data Source

PatentEP3364231B1Light scanning apparatus and image forming apparatus
Publication Date: 2025.08.13 CANON KK
  • EP3364231B1 patent drawingFigure 1
  • EP3364231B1 patent drawingFigure 2
  • EP3364231B1 patent drawingFigure 3

AI summary

A light scanning apparatus including: a first holder attached to a housing and configured to hold a first laser light source; a second holder attached to the housing and configured to hold a second laser light source; and a lens to which the laser lights are first incident, wherein the first holder and the second holder are attached to the housing in mutually different positions in a rotation axis direction of a rotary polygon mirror and in an optical axis direction of the lens, so that a first incident light path from the first laser light source to the rotary polygon mirror is placed between a second incident light path from the second laser light source to the rotary polygon mirror and the lens, and the first holder and the second holder overlap one another in the rotation axis direction.