Electrostatic Printer Voltage Control for Ink Layer Stability

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Solution Overview

Problem

In electrostatic printing systems, especially liquid electro-photographic (LEP) systems, variations in ink properties due to batch-to-batch variations or changes in concentration of solids and charging agents lead to unwanted toner transfer, increased ink consumption, reduced filter lifespan, and decreased print quality, as the developer voltage changes affect the operating window and dot gain.

Innovation Solution

The controller dynamically adjusts the charged voltage of the photoconductor member in response to changes in the developer voltage, maintaining a constant cleaning vector and adjusting the operating window to prevent unwanted toner transfer and stabilize dot gain, by increasing the charged voltage when the developer voltage increases, and using predefined functions or iterative processes to achieve optimal ink layer thickness and background reduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the developer voltage is changed to adjust ink layer thickness, then the ink layer thickness can be optimized, but the charged voltage becomes mismatched leading to unwanted toner transfer and increased ink consumption

Engineering Contradiction:
Improveink layer thicknessVSAvoidink consumption
Core Design Contradiction:
Manufacturing precisionVSLoss of substance

Solution Approach 1:

The patent applies dynamics by making the charged voltage adjustable and dependent on the developer voltage. Instead of using a fixed charged voltage, the system dynamically adapts the charged voltage based on the actual developer voltage being used, allowing the operating window to remain optimal even when developer voltage changes to adjust ink layer thickness.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of charged voltage in response to changes in developer voltage. By establishing a functional relationship between charged voltage and developer voltage, the system maintains the appropriate operating window regardless of developer voltage adjustments, preventing unwanted toner transfer and reducing ink consumption.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If the developer voltage is changed to adjust ink layer thickness, then the ink layer thickness can be optimized, but the print quality decreases due to unwanted toner transfer and dot gain variations

Engineering Contradiction:
Improveink layer thicknessVSAvoidprint quality
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The system dynamically adjusts the charged voltage based on the developer voltage, ensuring that the operating window remains stable even when developer voltage changes. This dynamic adaptation prevents dot gain variations and unwanted toner transfer, maintaining consistent print quality across different ink layer thickness settings.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements a feedback mechanism where the charged voltage is adjusted in response to the actual developer voltage being used. This feedback loop ensures that the operating window remains optimal, preventing print quality degradation that would otherwise occur when developer voltage changes are made to adjust ink layer thickness.

Inventive Principle:
Principle #23Feedback

3Device complexity

If a fixed charged voltage is used, then the system operation is simple, but the operating window becomes mismatched when developer voltage changes

Engineering Contradiction:
Improvevoltage control systemVSAvoidoperating window match
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent transitions from a static charged voltage system to a dynamic one where the charged voltage adjusts based on the developer voltage. This dynamic approach ensures that the operating window remains properly matched even when developer voltage changes, resolving the contradiction between system simplicity and operating window accuracy.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the charged voltage parameter in response to developer voltage changes. By establishing a functional relationship between these two parameters, the patent maintains optimal operating window matching without requiring complex additional hardware, balancing simplicity with precision.

Inventive Principle:
Principle #35Parameter changes

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 reduces unwanted ink accumulation, stabilizes dot gain, increases consumable lifespan, and enhances print quality by maintaining a dynamic operating window that adapts to changes in ink properties, thereby reducing ink consumption and extending machine utilization.

Implementation Method 1

a charging unit to charge the photoconductor member to a charged voltage

Methodology Applied
Scientific EffectElectrostatic charge: Electrostatics

Implementation Method 2

an imaging unit to generate a latent electrostatic image on the photoconductor member by discharging areas of the charged photoconductor member

Methodology Applied
Scientific EffectPhotoconductivity: Photoconductivity

Implementation Method 3

a developer unit to develop a toner image on the photoconductor member using a developer voltage

Methodology Applied
Scientific EffectElectrostatic deposition: Electrostatic Deposition

Data Source

PatentEP3250963B1Electrostatic printing system with charged voltage dependent on developer voltage
Publication Date: 2022.03.16 HP INDIGO BV
  • EP3250963B1 patent drawingFigure 1~2
  • EP3250963B1 patent drawingFigure 3A~3C
  • EP3250963B1 patent drawingFigure 4

AI summary

An electrostatic printer comprises a charging unit, a photoconductor member, an imaging unit, a developer unit and a controller, The charging unit is to charge the photoconductor member to a charged voltage. The imaging unit is to generate a latent electrostatic image on the photoconductor member by discharging areas of the charged photoconductor member. The developer unit is to develop a toner image on the photoconductor member using a developer voltage. The controller is to change the developer voltage, and to change the charged voltage dependent on the change of the developer voltage.