Process Cartridge Toner Density Sensor Agitation Mechanism

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Solution Overview

Problem

Existing toner density sensors in developing units for electrophotographic printing face detection errors due to developer accumulation on the detection surface, leading to fluctuations in detected toner density, which affects image quality and requires improved surface agitation techniques to maintain accurate toner density control.

Innovation Solution

A process cartridge design incorporating a detection surface agitating member with an elastic sheet and a planar member, both aligned at the same angle as the spiral screw blade, which rotates to scrape away developer accumulation while minimizing deformation and maintaining consistent toner density, thereby reducing detection errors and fluctuations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a toner density sensor is used to detect toner density in the developer container, then toner density control is achieved, but detection accuracy is degraded by developer accumulation on the detection surface

Engineering Contradiction:

Improvetoner density detection accuracyVSAvoiddeveloper accumulation on detection surface

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The conveyance screw performs dual functions: conveying developer and agitating the detection surface. The elastic sheet attached to the screw automatically scrapes developer accumulation during rotation, eliminating the need for separate cleaning mechanisms and maintaining continuous detection accuracy

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The elastic sheet continuously agitates and scrapes the detection surface before detection occurs, preventing developer accumulation from forming. This preliminary cleaning action ensures the detection surface remains clean and accurate throughout operation

Inventive Principle:

Principle #10Preliminary action

2Object-affected harmful factors

If an elastic sheet is used to scrape developer accumulation on the detection surface, then developer agitation is achieved, but detection values fluctuate in synchronization with the rotation cycle

Engineering Contradiction:

Improvedeveloper accumulation removalVSAvoidtoner density detection stability

Core Design Contradiction:

Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The elastic sheet performs periodic scraping actions during screw rotation. By optimizing the sheet's position, length, and elasticity, the periodic disturbance is minimized and the overall developer density at the detection surface is maintained, reducing detection fluctuations

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The elasticity and dimensions of the sheet are optimized to control the degree of developer agitation. The sheet's elastic properties allow it to gently scrape developer without creating excessive voids or density variations, minimizing detection value fluctuations

Inventive Principle:

Principle #35Parameter changes

3Reliability

If toner density is maintained at high levels to prevent background contamination, then image quality is improved, but toner consumption increases and detection accuracy decreases

Engineering Contradiction:

Improveimage quality consistencyVSAvoidtoner density detection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The toner density sensor provides continuous feedback on developer toner density. The controller uses this feedback to automatically replenish toner when density falls below the optimal range, maintaining consistent image quality while preventing background contamination through precise control

Inventive Principle:

Principle #23Feedback

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 prevents detection errors and maintains consistent toner density, enhancing image quality by reducing variations in developer density on the detection surface during agitation, thus improving the accuracy and reliability of toner density control.

Implementation Method 1

The detection surface agitating member includes an elastic sheet disposed at a substantially same angle to the axial direction of the shaft of the screw as the spiral screw blade and is elastically deformable to scrape away the developer accumulated on the detection surface

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

the two-component developer is mixed in a developer container so as to frictionally charge the two-component developer

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS8145100B2Process cartridge including developing unit and incorporated in image forming apparatus

Publication Date: 2012.03.27 RICOH CO LTD

AI summary

A process cartridge for use in an image forming apparatus includes an image bearing member and a developing unit. The developing unit includes a developer bearing member to bear developer including toner and carrier, a casing forming a developer container containing the developer, a screw having a shaft with a spiral screw blade, a toner density sensor to detect a density of the toner on a detection surface, and a detection surface agitating member fixedly mounted on the shaft of the screw at a position facing a detection surface to scrape away the developer accumulated on the detection surface as the screw rotates. The detection surface agitating member includes an elastic sheet elastically deformable to scrape away the developer accumulated on the detection surface and disposed at a substantially same angle to an axial direction of the shaft of the screw as the spiral screw blade.