Optical Sensor Light Guide Path for Grooved Surface Detection

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Solution Overview

Problem

Optical sensors used in image forming apparatuses face challenges in accurately detecting regularly-reflected light from surfaces with grooves, as diffracted light from these grooves interferes with the detection of regularly-reflected light, leading to reduced accuracy in toner image position and density control.

Innovation Solution

The optical sensor design includes a light-emitting element and a first light receiving unit mounted on a circuit board within a housing with specific openings that guide light paths, preventing diffracted light of +1st order and higher orders from incident on the light receiving unit, ensuring accurate detection of regularly-reflected light.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If grooves are formed in the surface of the intermediate transfer body to improve cleaning blade durability, then cleaning blade durability is improved, but regularly-reflected light from the substrate decreases and diffracted light increases

Engineering Contradiction:

Improvecleaning blade durabilityVSAvoiddetection accuracy of regularly-reflected light

Core Design Contradiction:

Duration of action of stationary objectVSMeasurement precision

Solution Approach 1:

The patent segments the light receiving function into two separate units: a first light receiving unit for receiving regularly-reflected light and a second light receiving unit for receiving diffused reflection light. This segmentation allows each unit to be optimized for its specific function, with the first unit positioned and configured to receive only regularly-reflected light from the substrate despite the presence of grooves.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a light guide as an intermediary component that guides light from the light emitting element to the intermediate transfer body and from the intermediate transfer body to the light receiving units. The light guide is configured to control the path of regularly-reflected light, ensuring it reaches the first light receiving unit while blocking diffracted light, thus mediating between the grooved surface and the detection system.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Illumination intensity

If diffracted light from grooves is incident on the light receiving unit, then the light receiving unit receives more total light, but the accuracy of detecting regularly-reflected light decreases

Engineering Contradiction:

Improvelight intensity receivedVSAvoiddetection accuracy

Core Design Contradiction:

Illumination intensityVSMeasurement precision

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by giving different light receiving units different positions, configurations, and functions. The first light receiving unit is positioned to receive only regularly-reflected light with specific angular characteristics, while the second light receiving unit is positioned to receive diffused reflection light. Each unit has localized optimization for its specific detection purpose.

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 enhances the accuracy of toner image position and density control by minimizing the impact of diffracted light, allowing for precise detection of toner amounts and image formation adjustments.

Implementation Method 1

diffracted light produced by a plurality of grooves acting as a diffraction grating

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 2

receives regularly-reflected light from the surface (substrate) of the intermediate transfer body

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 3

receives diffused reflection light from the toner to detect the toner

Methodology Applied

Scientific EffectDiffuse reflection: Scattering

Data Source

PatentUS11674893B2Structure of optical sensor having light-emitting element and light-receiving element

Publication Date: 2023.06.13 CANON KK

AI summary

A housing includes a first opening and a second opening, and encloses a light-emitting element and a first light receiving unit. The first opening is provided in a first light guide path, and is arranged so that light output from the light-emitting element travels toward a target surface. The second opening is provided in a second light guide path arranged between the target surface and the first light receiving unit. The first opening is an exit opening of a through-hole provided penetrating through the housing, and a shape of the through-hole is a shape in which diffracted light of the +1st order and higher orders and diffracted light of the −1st order and higher orders produced at the target surface to be irradiated are not incident on the first light receiving unit.