Printing Apparatus Transfer Protection via Conductive Discharge Path

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Solution Overview

Problem

Corona discharge between the photo imaging plate and intermediate transfer member in liquid electrophotographic printers leads to increased wear and reduced maintenance intervals due to oxidation of the intermediate transfer member, particularly when using epoxy-based print fluids, which exacerbates the issue.

Innovation Solution

Incorporating an electrically conductive member between the photo imaging plate and intermediate transfer member to provide a leakage path for corona discharge, reducing its impact on the transfer member by acting as a grounded conductor to attract and intercept the discharge.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an intermediate transfer member is used to transfer images in liquid electrophotographic printers, then image transfer capability is improved, but corona discharge causes oxidation and wear of the transfer member, reducing maintenance intervals

Engineering Contradiction:
Improveimage transfer capabilityVSAvoidmaintenance interval
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

A sacrificial conductive member is introduced as an intermediary between the photo imaging plate and the intermediate transfer member. This member intercepts corona discharge that would otherwise damage the intermediate transfer member, sacrificing itself instead. The conductive member is positioned in the corona discharge path and provides a preferred discharge route, protecting the expensive transfer member from oxidation and wear.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If corona discharge occurs between photo imaging plate and intermediate transfer member, then charging function is maintained, but oxidation of the transfer member increases, particularly with epoxy-based print fluids

Engineering Contradiction:
Improvecharging functionVSAvoidoxidation
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention converts the harmful corona discharge that damages the intermediate transfer member into a beneficial process by redirecting it onto a sacrificial conductive member. The corona discharge still performs its useful function of charging the photo imaging plate, but the harmful oxidation effect is transferred to the disposable conductive member instead of the valuable transfer member. This effectively separates the useful and harmful effects of corona discharge.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Productivity

If print fluid is applied to form intermediate images, then image formation is enabled, but adhesion between print fluid and intermediate transfer member increases, reducing releaseability

Engineering Contradiction:
Improveimage formation capabilityVSAvoidadhesion
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The sacrificial conductive member acts as a mediator that prevents direct harmful interaction between corona discharge and the intermediate transfer member. By intercepting the discharge, it maintains the transfer member's surface properties, ensuring optimal releaseability of print fluid. The conductive member's oxidation instead of the transfer member's oxidation prevents adhesion problems that would reduce image transfer quality.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Reduces oxidation and wear of the intermediate transfer member, thereby increasing maintenance intervals and improving print fluid releaseability, especially with epoxy-based fluids.

Implementation Method 1

Corona discharge between the photo imaging plate and intermediate transfer member in liquid electrophotographic printers leads to increased wear and reduced maintenance intervals due to oxidation of the intermediate transfer member

Methodology Applied
Scientific EffectCorona discharge: Corona Discharge

Implementation Method 2

Incorporating an electrically conductive member between the photo imaging plate and intermediate transfer member to provide a leakage path for corona discharge

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP4185925B1Printing apparatus
Publication Date: 2025.07.09 HEWLETT PACKARD DEVELOPMENT COMPANY LP
  • EP4185925B1 patent drawingFigure 1
  • EP4185925B1 patent drawingFigure 2~3
  • EP4185925B1 patent drawingFigure 4

AI summary

A printing apparatus has a photo imaging plate to be held at a first voltage having a first polarity, and an intermediate transfer member to receive an intermediate image from the photo imaging plate. The intermediate transfer member is to be held at a second voltage having a second polarity opposite to the first polarity. An electrically conductive member is disposed between the photo imaging plate and the intermediate transfer member.