Liquid Developer Transfer Bias Control via Carrier Liquid Supply

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Solution Overview

Problem

In image forming apparatuses using liquid developers, fluctuations in resistance values due to the presence or absence of carrier liquid during image formation lead to deviations in transfer bias, resulting in inefficient or improper transfer of toner images.

Innovation Solution

The implementation of an Active Transfer Voltage Control (ATVC) system that sets the transfer bias based on real-time voltage and current detections during non-image formation, ensuring the carrier liquid is present at the transfer portion, thereby stabilizing the resistance value and maintaining optimal transfer conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If transfer bias setting control is performed at timing other than during image formation, then transfer efficiency is improved for dry developers, but transfer bias deviates for liquid developers due to resistance value fluctuations

Engineering Contradiction:
Improvetransfer efficiencyVSAvoidtransfer bias accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The invention performs preliminary action by supplying carrier liquid to the transfer portion before executing transfer bias setting control. This ensures that the resistance value measurement is performed under conditions matching actual image formation, thereby accurately determining the transfer bias that compensates for resistance fluctuations in liquid developers.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention changes the physical state parameter of the transfer portion by supplying carrier liquid to transition from a dry state (during non-image formation) to a wet state (during image formation). This parameter change ensures that the resistance value measured during bias setting reflects the actual conditions during toner image transfer.

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If carrier liquid is present during transfer bias setting, then resistance value stability is improved, but additional control complexity is introduced

Engineering Contradiction:
Improveresistance value stabilityVSAvoidcontrol system complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The invention employs self-service by automatically controlling the carrier liquid supply mechanism to provide carrier liquid to the transfer portion before transfer bias setting control is executed. This automatic control eliminates the need for manual intervention or complex external monitoring systems, thereby achieving resistance value stability without significantly increasing device complexity.

Inventive Principle:
Principle #25Self-service

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 approach ensures consistent and efficient transfer of toner images by maintaining the desired transfer bias, even with fluctuations in resistance values, thereby preventing excess or deficiency of electric charges during image formation.

Implementation Method 1

a voltage-current detection circuit that detects voltage and current at a transfer portion

Methodology Applied
Scientific EffectOhm's Law: Ohm's Law

Implementation Method 2

transfer means that applies electric charges to a transfer-receiving material

Methodology Applied
Scientific EffectElectrostatic attraction: Electrostatic Induction

Data Source

PatentEP3255503B1Image forming apparatus
Publication Date: 2022.11.02 CANON KK
  • EP3255503B1 patent drawingFigure 1
  • EP3255503B1 patent drawingFigure 2
  • EP3255503B1 patent drawingFigure 3

AI summary

An image forming apparatus includes an image bearing member; a transfer member configured to form a transfer portion where the toner image is transferred from the image bearing member by being supplied with a transfer bias; a carrier liquid supplying portion configured to supply the carrier liquid to the transfer portion; a transfer bias voltage source capable of applying the transfer bias to the transfer portion; a detecting portion configured to detect at least one of a voltage and a current at the transfer portion; and a setting portion configured to set the transfer bias during non-image-formation on the basis of a detection result of the detecting portion when a setting bias is applied from the transfer member in a state in which the carrier liquid is in the transfer portion.