Developer Amount Detector Light Path Positioning

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Solution Overview

Problem

Existing developer amount detectors in image forming apparatuses face accuracy issues due to fluctuations in the toner surface caused by the rotation of developer conveyance screws, leading to unreliable detection of toner levels, especially in configurations with developer conveyance members like screws.

Innovation Solution

The developer amount detector includes a light-emitting element, a light-receiving element, and light guides positioned such that the light transmission path is within the locus of rotation of the developer conveyance member, ensuring a stable light path and accurate detection by minimizing interference from the conveyance mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a developer conveyance screw is used to transport developer, then local shortage of developer is prevented, but detection accuracy of light transmission-type developer amount detectors is degraded due to surface fluctuations

Engineering Contradiction:

Improvedeveloper supply stabilityVSAvoiddeveloper amount detection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

A light shield is introduced as an intermediary component between the light source and the developer surface. This light shield extends in the axial direction of the conveyance screw and positions the light transmission path within the locus of rotation of the screw, allowing light to pass through a region less affected by surface fluctuations while still detecting developer amount accurately

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The light transmission path is repositioned from a horizontal arrangement to an axial arrangement parallel to the conveyance screw axis. This dimensional change allows the light to travel through a region that is more stable during screw rotation, reducing the impact of surface fluctuations on detection accuracy

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Device complexity

If light transmission path is positioned perpendicular to conveyance screw axis, then simple detector configuration is achieved, but detection accuracy is reduced due to light path interference from rotating screw

Engineering Contradiction:

Improvedetector configuration simplicityVSAvoidtoner detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The light transmission path is reoriented from perpendicular to the screw axis to parallel with the screw axis. This dimensional repositioning places the light path within the locus of rotation, allowing the light to pass through a more stable region while maintaining a relatively simple detector configuration

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The light shield is positioned in advance to define the light transmission path before the light reaches the developer surface. This preliminary positioning ensures that the light travels through a region less affected by surface fluctuations, preventing detection errors before they occur

Inventive Principle:

Principle #10Preliminary action

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 detection, reducing errors and ensuring timely replacement of developer containers, thus maintaining image quality and preventing insufficient toner density.

Implementation Method 1

a light-emitting element to emit light

Methodology Applied

Scientific EffectLight emission: Light

Implementation Method 2

the light transmission path is positioned partly inside a locus of rotation of the first developer conveyance member

Methodology Applied

Scientific EffectLight transmission: Light

Implementation Method 3

a light-receiving element... the light can reach the light-receiving element

Methodology Applied

Scientific EffectLight detection: Photoelectric Effect

Data Source

PatentUS8861991B2Developer amount detector, and developer container, development device, and image forming apparatus incorporating same

Publication Date: 2014.10.14 RICOH CO LTD

AI summary

A development device includes a development housing, a first developer conveyance member, a developer bearer, and a developer amount detector to detect an amount of developer in the development housing. The developer amount detector includes a light-emitting element, a right-receiving element, a first light guide including a first end from which light enters and a second end disposed inside the development housing, and a second light guide including a first end positioned inside the development housing across a predetermined distance from the second end of the first light guide and a second end from which the light exits. The second end of the first light guide and the first end of the second light guide are arranged in an axial direction of the first developer conveyance member with a light transmission path therebetween partly inside a locus of rotation of the first developer conveyance member.