Rounded Wiper Edge Maintains Cleaning Solution Layer on Photoconductive Drum

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Solution Overview

Problem

Photoconductive drums with longer lifespans in electrophotographic printing devices suffer from image quality degradation due to dirt and debris accumulation, as conventional cleaning methods fail to maintain image quality over their extended lifespan.

Innovation Solution

Maintaining a relatively thick layer of cleaning solution on the photoconductive drum, achieved by rounding the edge of the wiper to ensure a cleaning solution layer greater than 100 nanometers in thickness, which promotes drum longevity and protects against contaminants without interfering with charging processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional cleaning methods are used on photoconductive drums, then the drum surface is cleaned, but image quality degrades over extended drum lifespan due to dirt and debris accumulation

Engineering Contradiction:
Improveimage quality consistencyVSAvoiddrum lifespan
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the physical parameter of the cleaning solution layer thickness from the conventional thin layer to a relatively thick layer (greater than 100 nanometers). This parameter change allows the cleaning solution to remain effective at removing contaminants over extended drum lifespans, maintaining image quality consistency without the degradation that occurs with conventional thin-layer cleaning methods.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies curvature to the wiper edge (rounding it) to prevent the wiper from completely removing the cleaning solution from the photoconductive drum surface. This curved geometry ensures that a relatively thick layer of cleaning solution (greater than 100 nanometers) remains on the drum, enabling continuous effective cleaning throughout the drum's extended operational life.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Reliability

If a thick layer of cleaning solution is maintained on the photoconductive drum, then contaminants are effectively removed and drum longevity is promoted, but the charging process may be interfered with

Engineering Contradiction:
Improvecontaminant removal effectivenessVSAvoidcharging process interference
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies partial action by maintaining a cleaning solution layer thickness that is greater than 100 nanometers but controlled to not completely prevent charging. This partial thickness is sufficient to protect the drum surface and remove contaminants effectively, while allowing the charging process to occur, thus balancing contaminant removal with charging functionality.

Inventive Principle:
Principle #16Partial or excessive action

3Strength

If the wiper edge is rounded to maintain cleaning solution layer, then drum surface is protected from damage, but the wiper structure becomes more complex

Engineering Contradiction:
Improvedrum surface protectionVSAvoidwiper structure
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent applies curvature to the wiper edge to create a rounded profile. This simple geometric modification protects the photoconductive drum surface from damage by preventing the sharp edge from scratching or abrasing the drum, while maintaining the structural simplicity of the wiper component.

Inventive Principle:
Principle #14Spheroidality (Curvature)

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 extends the ability of photoconductive drums to form images without quality impairment, protects the drum from damage, and ensures effective removal of contaminants, while maintaining operational efficiency throughout the drum's lifespan.

Implementation Method 1

Maintaining a relatively thick layer of cleaning solution on the photoconductive drum, achieved by rounding the edge of the wiper to ensure a cleaning solution layer greater than 100 nanometers in thickness, which promotes drum longevity and protects against contaminants

Methodology Applied
Scientific EffectProtective barrier:

Implementation Method 2

a photoconductive drum is charged over its entire surface, and then selectively discharged in accordance with the image to be formed

Methodology Applied
Scientific EffectPhotoconductivity: Photoconductivity

Implementation Method 3

Charged colorant such as dry or liquid ink or toner adheres to locations on the drum that have been discharged

Methodology Applied
Scientific EffectElectrostatic attraction: Electrostatics

Data Source

PatentEP3278182B1Electrophotographic printing
Publication Date: 2021.07.28 HP INDIGO BV
  • EP3278182B1 patent drawingFigure 1
  • EP3278182B1 patent drawingFigure 2~4
  • EP3278182B1 patent drawingFigure 5

AI summary

A cleaning solution is used to at least substantially remove colorant from the photoconductive drum as the photoconductive drum rotates. A wiper wipes the cleaning solution from the photoconductive drum while purposefully maintaining a layer of the cleaning solution on the drum. The wiper has an edge that is purposefully rounded.